Thinkers Timeline

Imhotep was an ancient Egyptian architect, doctor, and high official. He lived around 2,650 BCE, more than 4,500 years ago. This makes him one of the earliest individuals in history whose name and work we still know. He served the pharaoh Djoser, third king of Egypt's Third Dynasty. Most of what we know about him comes from later inscriptions and traditions. He was probably born to ordinary parents, not from the royal family. He rose through his own talent. He held many titles at Djoser's court. Inscriptions from his time call him chancellor, high priest of the sun god Ra at Heliopolis, and chief carpenter and sculptor. He may also have served as the king's chief doctor. He was clearly one of the most important people in the kingdom, second only to the pharaoh himself. His greatest known work is the Step Pyramid at Saqqara. It was built as a tomb for Djoser. Before this pyramid, Egyptian kings were buried in flat-topped mud-brick tombs called mastabas. Imhotep stacked six mastabas of decreasing size on top of each other and built them in stone, not mud. The result was the world's first large stone building. It still stands today. After his death, Imhotep's reputation grew over the centuries. By around 500 BCE, more than 2,000 years after his life, he was being worshipped as a god of medicine and wisdom. The Greeks later identified him with their own healing god Asclepius. His tomb has never been found.

Confucius (551-479 BCE) was a Chinese thinker, teacher, and social philosopher. His Chinese name was Kong Qiu, and he is also known as Kongzi, meaning Master Kong. He was born in the state of Lu, in what is now Shandong Province in eastern China, during a period of political disorder known as the Spring and Autumn period, when the Zhou dynasty was fragmenting into competing states. He came from a family that had once been aristocratic but had fallen into genteel poverty. He worked as a teacher for most of his life, believing that education and moral cultivation could transform both individuals and societies. He also worked for a time as a government official, hoping to put his ideas into practice, but became disillusioned and eventually left to travel and teach. He never wrote a book himself: his ideas are preserved in the Analects, a collection of his conversations and sayings compiled by his students after his death. He died in 479 BCE, probably believing that he had failed to influence his world. In fact, his ideas went on to shape the culture, governance, and social life of China and much of East and Southeast Asia for two and a half thousand years.

Herodotus (c.484-425 BCE) was an ancient Greek writer, born in Halicarnassus, a city on the southwestern coast of what is now Turkey. He lived during one of the most dramatic periods in the ancient world: the wars between the Greek city-states and the Persian Empire. He is called the father of history, a title given to him by the Roman writer Cicero, because he was the first person we know of who systematically investigated the past through inquiry and travel rather than simply recording myths or royal chronicles. The word history itself comes from the Greek word he used in the opening of his work, historie, meaning inquiry or investigation. He travelled extensively across the known world, visiting Egypt, the Persian Empire, Scythia in what is now Ukraine and Russia, and many other places. He talked to people, visited sites of important events, collected stories, and tried to understand why things had happened. His great work, which we call The Histories, tells the story of the wars between Greece and Persia but ranges far beyond this into the customs, geography, and history of dozens of peoples. He died around 425 BCE, probably in the Greek colony of Thurii in southern Italy.

The Buddha was a teacher who lived in northern India around 2,500 years ago. His personal name was Siddhartha Gautama. 'Buddha' is a title. It means 'the awakened one' or 'the one who is awake'. Most scholars now think he lived from about 480 to 400 BCE, though older tradition gives earlier dates. He was born a prince of the Shakya clan, in what is now southern Nepal. The traditional story says his father tried to keep him from seeing suffering. The young prince lived in palaces full of beauty and pleasure. He married and had a son. Then, around the age of 29, he saw four things outside the palace: an old man, a sick man, a dead man, and a wandering holy man. These sights changed him. He left his family and his comfortable life. He spent six years living as a wanderer. He tried very strict self-denial, eating almost nothing. This nearly killed him. He gave up extreme practices. He sat under a tree at a place now called Bodh Gaya and meditated. He said he reached awakening, a deep understanding of how suffering works and how to end it. He spent the next 45 years teaching across northern India. He gathered followers and built a community of monks and nuns. He died around the age of 80. His teachings became one of the world's major religions and philosophies.

Socrates (c. 470–399 BCE) was a philosopher in ancient Athens, Greece. He wrote nothing himself — everything we know about him comes from the writings of his students, especially Plato. He spent his life in the streets and public spaces of Athens, asking people questions about the things they claimed to know — justice, courage, virtue, knowledge. He was famously described as the wisest man in Athens, but said this could only be true because he alone knew that he knew nothing. In 399 BCE he was put on trial by the Athenian government, charged with corrupting the youth and not respecting the gods. He was found guilty and sentenced to death by drinking poison. He refused to escape when he had the chance, saying a philosopher must obey the law even when it is unjust.

Hippocrates (c. 460-370 BCE) was an ancient Greek physician, born on the island of Cos. He is one of the most important figures in the history of medicine, often called the father of medicine, though this title should be understood carefully: he was not the first person to practise healing but the founder of a tradition that understood medicine as a rational discipline based on careful observation rather than on supernatural explanations. Very little is known about his actual life. What we have is the Hippocratic Corpus, a collection of about sixty medical texts that were associated with his school, though they were probably written by many different authors over several generations. These texts cover anatomy, clinical observation, surgery, diet, and medical ethics. They represent the first systematic attempt to study disease through observation and reason, and to develop a set of ethical principles that should govern the relationship between physician and patient. The Hippocratic Oath, though its exact origin is debated, became the foundation of medical ethics across the Western world and beyond.

Plato was an ancient Greek philosopher. He is one of the most important thinkers in human history. The whole tradition of Western philosophy has been called 'a series of footnotes to Plato'. He was born around 428 BCE in Athens, the great Greek city of his time. He died around 348 BCE, aged about 80. He came from a wealthy aristocratic family. His real name was probably Aristocles. 'Plato' (meaning 'broad' in Greek) seems to have been a nickname, possibly from his physical build. As a young man, he expected to enter politics. The political life of Athens, however, made him turn away. He was a student of Socrates, the philosopher who walked the streets of Athens questioning everyone. In 399 BCE, when Plato was about 29, the Athenian democracy executed Socrates on charges of corrupting the young and disrespecting the gods. Plato never got over it. The death shaped his philosophy and his deep distrust of democracy. After Socrates' death, Plato travelled. He went to southern Italy, Sicily, and possibly Egypt. Around 387 BCE, he returned to Athens and founded the Academy, a school for philosophy. The Academy lasted in some form for nearly 900 years. Aristotle studied there as a young man. Plato wrote about 35 dialogues, almost all of which survive. The dialogues are conversations, usually with Socrates as the main speaker. They cover almost every philosophical topic: justice, knowledge, beauty, love, the soul, government, education. The Republic is his most famous. The Symposium and the Phaedo are also widely read. He died in his eighties, still teaching at the Academy.

Aristotle was an ancient Greek philosopher. He is one of the most important thinkers in the history of Western philosophy and science. He was born in 384 BCE in Stagira, a small city in northern Greece. His father was a doctor to the royal court of Macedonia. At seventeen, Aristotle travelled to Athens and joined the Academy, the school founded by Plato. He stayed there for twenty years as a student and then as a teacher. When Plato died in 347 BCE, Aristotle left Athens. He travelled, taught, and did natural history research on the island of Lesbos. Around 343 BCE, he was invited by King Philip II of Macedonia to tutor Philip's son, the teenager who would become Alexander the Great. This is one of the most famous teacher-student relationships in history, though its actual influence on Alexander is hard to measure. In 335 BCE, Aristotle returned to Athens and founded his own school, the Lyceum. He taught there for twelve years and wrote many of his most important works. After Alexander's death in 323 BCE, anti-Macedonian feeling in Athens made Aristotle's position dangerous. He fled the city, reportedly saying he would not let Athens 'sin twice against philosophy', a reference to the execution of Socrates. He died a year later in 322 BCE, aged 62. His surviving works, which are mostly lecture notes rather than polished books, cover logic, biology, psychology, ethics, politics, poetry, rhetoric, and metaphysics. Together they shaped Western thought for more than two thousand years. Almost every field of inquiry has at some point been measured against Aristotle.

Mencius was a Chinese philosopher. His Chinese name was Meng Ke, which means 'Master Meng'. Later Chinese tradition called him the 'Second Sage', meaning second only to Confucius himself. The Latin name 'Mencius' was given to him by European Jesuit missionaries in the 17th century. He was born around 371 BCE in the small state of Zou, in what is now Shandong province in eastern China. This was the same region where Confucius had lived over a century earlier. Mencius's father died when he was three years old. His mother raised him alone. Stories about her wisdom became famous in China. In one story, she moved house three times to find a place where her son would have good influences around him. The story of 'Mencius's Mother's Three Moves' is still told in China today. Mencius lived during the Warring States Period. This was a violent time. Several Chinese kingdoms fought each other constantly. Armies swept across the land. Ordinary people suffered terribly from war, high taxes, and harsh rulers. Mencius spent much of his adult life travelling from one kingdom to another, offering advice to their rulers. He wanted them to govern more humanely. Some listened for a while. Most did not take his advice seriously. In the end, he retired from public life, disappointed. His students collected his conversations and teachings in a book. It is called simply the Mencius. The book is long and often funny. Mencius argues with rulers, other philosophers, and his own students. He is sharp, stubborn, and clear. He died around 289 BCE, aged about 82. Nearly 1500 years later, the Mencius became one of the 'Four Books' that every educated Chinese person had to study. His ideas shaped China, Korea, Japan, and Vietnam for centuries.

Zhuangzi was a Chinese philosopher of the 4th century BCE. His name means 'Master Zhuang'. His personal name was Zhuang Zhou. He lived during a period called the Warring States, when several Chinese kingdoms fought each other constantly. This was a violent and unstable time. It was also a golden age of Chinese thought. Many of China's most important thinkers lived then: Confucius had lived a generation earlier, Mencius and Laozi were also writing in this period. We know very little for certain about Zhuangzi's life. The historian Sima Qian, writing about 150 years after his death, says he was a minor official in a place called Qiyuan, in what is now Henan province. He was offered a high position by the king of the state of Chu but turned it down. He preferred to live simply. He married and had children. He died in peace, probably in his sixties. The book known as the Zhuangzi is named after him. It has 33 chapters and is one of the great works of world literature. Modern scholars think Zhuangzi himself wrote only the first seven chapters, sometimes called the 'Inner Chapters'. These contain the most famous and powerful writing. The rest of the book was written by his students and later followers over several generations. The Zhuangzi is, along with the Daodejing, the foundation of Daoist philosophy. Together the two books form the core of the Daoist tradition. Unlike most philosophers of his time, Zhuangzi wrote mostly in stories. His book is full of talking animals, wise cooks, strange encounters, and dream sequences. He is one of the first great storytellers in world philosophy. His influence on Chinese literature, art, and humour has been enormous.

Euclid was a Greek mathematician who lived in Alexandria, in Egypt, around 300 BCE. He is sometimes called the 'father of geometry'. We know almost nothing about his personal life. We do not know where he was born, who his parents were, or when exactly he died. We are not even certain he was a single person. Some scholars have wondered whether 'Euclid' might be a name used by a group of mathematicians. What we do know is that he worked at the Library and Museum of Alexandria. This was the great centre of learning in the ancient world, founded by the kings of Egypt after Alexander the Great. Scholars from across the Greek world gathered there. Euclid taught and wrote in this setting. His great work is called the Elements. It is a textbook of geometry and number theory in 13 books. The Elements gathered together the mathematical work of earlier Greek thinkers like Pythagoras, Eudoxus, and Theaetetus. It also added Euclid's own arrangement and proofs. The Elements was used as the main geometry textbook for over 2,000 years. Until the late 19th century, almost every educated person in Europe and the Middle East had studied it. It was translated into Arabic, Latin, English, and many other languages. It is one of the most printed and studied books in human history, after only the Bible. Euclid himself remains a quiet mystery behind his enormous influence.

Archimedes was a Greek mathematician, scientist, and engineer. He was born around 287 BCE in Syracuse, a Greek city on the island of Sicily. We know little about his early life. His father was an astronomer named Phidias. He may have studied for a time at the great Library of Alexandria in Egypt, though this is not certain. Most of his life, however, was spent in Syracuse. In his time, Syracuse was an independent Greek-speaking city. The Roman Republic was growing stronger and would soon swallow most of the Mediterranean world. Archimedes worked closely with the king of Syracuse, Hiero II, and later with Hiero's grandson Hieronymus. He served the city as both a thinker and an inventor. In the year 212 BCE, Roman forces attacked Syracuse. Archimedes was about 75 years old. He had designed weapons to defend the city, including powerful catapults and machines that lifted enemy ships out of the water. The Romans took the city after a long siege of about two years. The traditional story is that a Roman soldier killed Archimedes during the chaos, even though the Roman general Marcellus had ordered that he be spared. According to later writers, Archimedes was working on a mathematical problem when the soldier arrived. He asked not to have his diagrams disturbed. The soldier killed him anyway. His tomb in Syracuse was lost for centuries. The Roman writer Cicero claimed to have rediscovered it nearly 140 years after his death.

Sima Qian was a Chinese historian and writer. He lived from around 145 BCE to about 86 BCE, during the Western Han dynasty. He is often called the father of Chinese history. His great work, the Shiji or Records of the Grand Historian, set the model for how history was written in China for the next 2,000 years. He was born in a small town in what is now Shaanxi province, in central China. His father, Sima Tan, was a court historian and astronomer at the imperial court of Emperor Wu. Sima Qian was educated as a scholar and travelled widely across the Han empire as a young man. He visited important historical sites and gathered materials for what would become his great work. When his father died in 110 BCE, Sima Qian inherited the position of grand historian. In 99 BCE, his life took a terrible turn. A Han general named Li Ling had surrendered to the Xiongnu, a nomadic enemy people. Sima Qian defended Li Ling at court. The emperor was furious. Sima Qian was sentenced to death. He could escape death only by paying a fine he could not afford or by accepting castration. Most men of his class would have chosen suicide. Sima Qian chose castration. He explained later that he had to live to finish his history. The choice was deeply shameful in his society but allowed him to complete the Shiji. He finished the work around 91 BCE and died a few years later. The Shiji has been read continuously ever since.

Marcus Tullius Cicero was a Roman lawyer, statesman, philosopher, and writer. He is one of the most influential figures in the history of Western law and political thought. He was born on 3 January 106 BCE in Arpinum, a small town about 70 miles south-east of Rome. His family was wealthy but not noble. They belonged to the equestrian class, the second tier of Roman society below the senators. His parents wanted him to rise. They sent him to Rome and then to Greece for the best education available. He studied law, rhetoric (the art of public speaking), and philosophy. By his mid-twenties he was working as a lawyer in Rome. He rose quickly. He became famous for his speeches in court cases. In 63 BCE, at the age of 43, he was elected consul, the highest political office in Rome. That year he uncovered the Catiline Conspiracy, a plot to overthrow the Roman state. The Senate executed the conspirators on Cicero's authority. The Romans gave him the title 'Father of the Country'. His later career was difficult. He was exiled briefly in 58 BCE. The Roman Republic was collapsing. Julius Caesar took dictatorial power. After Caesar was assassinated in 44 BCE, Cicero attacked Mark Antony in a series of fierce speeches called the Philippics. Antony, Octavian, and Lepidus formed the Second Triumvirate and made lists of enemies to be killed. Cicero was on the list. He was caught and executed on 7 December 43 BCE, aged 63. His severed head and hands were displayed in the Roman Forum.

Ban Zhao was a Chinese historian, poet, and teacher of the Eastern Han dynasty. She is the first known woman historian of China. She was born around 45 CE in Anling, near modern Xianyang in Shaanxi province. Her family was a famous scholarly household. Her father Ban Biao was a respected scholar and historian. Her two older twin brothers, Ban Gu and Ban Chao, would also become important figures. She was educated at home by both her parents. This was unusual for a girl, even in a scholarly family. By her teens she was widely read in Chinese classics. At fourteen she married Cao Shishu, a local man. They had several children. Her husband died young. She did not remarry, which was already considered virtuous in her culture. Her father had been writing a major history of the Western Han dynasty (206 BCE to 23 CE). After his death, her brother Ban Gu took over the project. In 92 CE, Ban Gu was imprisoned because of court politics and died in prison. Around 97 CE, the emperor summoned Ban Zhao to the capital to finish her brother's work. She was given access to the Imperial Library, an extraordinary privilege for any scholar of her time. She completed the Book of Han (Han shu), one of the most important histories ever written in China. She also wrote Lessons for Women (Nüjie) and many other works. She tutored the empress and other women of the court. She died around 117 CE, aged about 70.

Marcus Aurelius (121-180 CE) was Roman Emperor from 161 until his death in 180 CE, and one of the most important philosophers in the Stoic tradition. He was born in Rome into a prominent family and was adopted by the emperor Antoninus Pius, who trained him carefully for rule. He received an excellent education in rhetoric and philosophy, and was particularly drawn to Stoic philosophy, which he studied seriously from his teenage years. He came to power in 161 CE and ruled for nearly two decades, spending much of his reign on military campaigns defending the empire's northern frontier against Germanic tribes. He died in 180 CE, probably of plague, at his military camp. His personal philosophical notebook, known as the Meditations, was almost certainly never intended for publication: it is a private record of his ongoing effort to live according to Stoic principles, written largely in Greek during his years on campaign. It survived by chance. It is one of the most widely read philosophical texts in the world and has been continuously in print since the Renaissance.

Epictetus (c.50-135 CE) was a Greek Stoic philosopher who was born into slavery in Hierapolis, a city in what is now Turkey. His name means acquired, or something like the purchased one, which reflects his status. He was owned by a freedman named Epaphroditus who worked in the imperial court of the Emperor Nero in Rome. Epictetus was permitted to study philosophy, and he became a student of the Stoic teacher Musonius Rufus. He was eventually freed, probably after Nero's death, and established his own philosophical school first in Rome and later, after the Emperor Domitian expelled philosophers from Rome, in the city of Nicopolis in northwestern Greece. He was lame, probably as a result of mistreatment during his time in slavery, though ancient accounts of the specific circumstances differ. He left no writings himself: everything we have from him is in the notes taken by his student Arrian, who compiled them into two works, the Discourses and the shorter Enchiridion or Handbook. He had an enormous influence on later Stoic thinkers including Marcus Aurelius.

Nagarjuna (approximately 150-250 CE) was an Indian Buddhist philosopher, widely considered one of the most important and influential thinkers in the entire history of Asian philosophy. He was born in South India, probably in what is now Andhra Pradesh, and became a Buddhist monk and teacher. He is the founder of the Madhyamaka school of Buddhist philosophy, which became one of the dominant schools of Buddhist thought across India, Tibet, China, Korea, Japan, and Southeast Asia. Very little is known about his life as a historical person: later tradition attributed extraordinary feats and a legendary biography to him, making it difficult to separate fact from story. What we do have are his philosophical texts, above all the Mulamadhyamakakarika, the Fundamental Verses on the Middle Way, a short but extraordinarily dense philosophical work in verse form that argues for one of the most radical positions in the history of philosophy: that nothing whatsoever has fixed, independent existence. He died sometime in the second or third century CE, but his ideas have continued to shape Buddhist philosophy and practice across Asia for nearly two thousand years.

Origen was an early Christian scholar and teacher. He was born around 184 CE in Alexandria, in Roman Egypt, and died around 253 CE. He is one of the most important thinkers of the early Church, and also one of the most argued about. He grew up in a Christian family during a time when Christians were sometimes persecuted by the Roman state. When Origen was a teenager, his father was killed for his faith. Origen wanted to die with him but was stopped. This early loss shaped his whole life. He became a serious, hard-working, and intense person. While still young, he began teaching Christian students in Alexandria. He read widely, including Greek philosophy and the work of the Jewish thinker Philo, who had lived in the same city long before. Origen wrote a huge amount: commentaries on the Bible, defences of the faith, and works of theology. Later he moved to the city of Caesarea, where he set up a school. During a wave of persecution under the emperor Decius, around 250 CE, Origen was arrested and tortured. He did not give up his faith. He survived the prison but his body was broken by the treatment, and he died a few years later. The Church never officially named him a saint, partly because some of his ideas were later judged to be mistaken.

Hypatia of Alexandria (c.350-415 CE) was a mathematician, astronomer, and philosopher who taught in the Egyptian city of Alexandria during the late Roman Empire. She was the daughter of the mathematician Theon, a scholar connected to the great library of Alexandria, and she received an exceptional education in the mathematical and philosophical traditions of the Greek-speaking world. By her maturity she was a renowned teacher in the Neoplatonist tradition, giving public lectures and leading a private circle of students that included Christians, pagans, and members of the wealthy families of the eastern Roman Empire. She is known to have written commentaries on the great mathematical texts of her time, including Diophantus's Arithmetica, Apollonius's Conics, and Ptolemy's Almagest, and to have worked closely with her father on the preservation and editing of earlier mathematical works. Her own writings do not survive; we know her through letters from her students, particularly Synesius of Cyrene, who became a Christian bishop but continued to honour her as his intellectual guide. Alexandria in her lifetime was politically and religiously turbulent. In 415 CE she was killed by a Christian mob in the streets of the city, in circumstances that have been debated by historians ever since. Her death has been remembered for sixteen centuries as a marker of something lost.

Augustine of Hippo was a Christian bishop, theologian, and writer in late Roman North Africa. He is one of the most influential Christian thinkers in history. His ideas shaped Western Christianity for over 1,500 years and continue to do so. He was born in 354 CE in Thagaste, in what is now Algeria. He died in 430 CE in Hippo Regius, a North African city now also in Algeria. He came from a mixed religious household. His father Patricius was a Roman pagan official who converted to Christianity only on his deathbed. His mother Monica was a devout Christian who pushed for her son's conversion for years. Augustine was a clever boy. He studied rhetoric in Carthage, the major North African city. He moved to Rome and then to Milan as a teacher of rhetoric. He took a long-term partner who is unnamed in his writings. They had a son together. He sent her away when his mother arranged a more socially advantageous marriage that he never made. As a young man he was attracted to Manichaeism, a religion that mixed Christian, Persian, and Buddhist elements. He spent nine years as a Manichaean. He found its answers eventually unsatisfying. In Milan, under the influence of Bishop Ambrose and his own reading of Plato and the New Testament, he converted to Christianity in 386. He was 31. His mother died shortly after, having seen what she had wanted. He returned to North Africa. He became a priest in 391, then bishop of Hippo in 395. He served as bishop for 35 years. He wrote constantly. His Confessions (around 400 CE) is one of the first major spiritual autobiographies. His City of God (begun 413) is a vast work of theology and political thought. He died as Vandal armies were besieging his city.

Boethius was a Roman scholar and statesman who lived during the collapse of the Western Roman Empire. His full name was Anicius Manlius Severinus Boethius. He is sometimes called 'the last of the Romans and the first of the Scholastics'. He was born around 480 CE in Rome, into a noble Christian family. He died in 524 CE, executed by King Theodoric the Ostrogoth on charges of treason. The western Roman Empire had fallen in 476 CE, four years before Boethius was born. Italy was now ruled by the Ostrogoths, a Germanic people. King Theodoric ran the country, but he respected Roman traditions and employed Roman officials. Boethius came from one of the leading senatorial families. His father had been consul. Boethius himself became consul in 510, then magister officiorum (a senior court position) under Theodoric. He was a serious scholar as well as a politician. He set himself an enormous project: to translate all of Plato and Aristotle into Latin and to show that the two philosophers ultimately agreed. He never finished. He completed important translations of Aristotle's works on logic, with extensive commentaries. These translations were the only direct access most of medieval Europe had to Aristotle for over 600 years. He also wrote original works on music, mathematics, and theology. In 523, Boethius was accused of treason. The charges involved his defence of a senator and possibly secret communication with the Eastern Roman Emperor in Constantinople. Boethius denied wrongdoing. Theodoric, perhaps growing suspicious of his Christian Roman elite, had him imprisoned. While in prison awaiting execution, Boethius wrote his most famous book, the Consolation of Philosophy. He was executed in 524 by being beaten or strangled. He was about 44.

Laozi is the name given to the author of the Daodejing, one of the most important books in Chinese thought. The name means 'Old Master'. We do not know if Laozi was a real person. The traditional story says he lived in the 6th century BCE, in the same period as Confucius. He is said to have worked as a keeper of royal records in the Zhou court. When the Zhou kingdom began to fall apart, he decided to leave. At the western gate, a guard asked him to write down his wisdom before he left. The result was the Daodejing, a short book of about 5,000 Chinese characters. Then Laozi rode away on a water buffalo and was never seen again. Most modern scholars think this story is a legend. The book was probably written by several people over time, and the oldest parts may come from the 4th century BCE, not the 6th. The name 'Laozi' may have been a title for a group of teachers rather than one person. But the book itself is real, and it has shaped Chinese culture for more than two thousand years. The Daodejing is the founding text of Daoism (also spelled Taoism). Daoism became one of the three main traditions of Chinese thought, alongside Confucianism and Buddhism. These three shaped China, Korea, Japan, and Vietnam for centuries. Daoism is both a philosophy and, later, a religion with temples, priests, and rituals. Laozi himself, real or not, became a god in the religious tradition. Statues of him stand in temples across China and East Asia today.

Philo of Alexandria was a Jewish philosopher who lived in Egypt. He was born around 20 BCE and died around 50 CE. Alexandria, his home city, was one of the largest and most learned cities in the ancient world. It had a big Jewish community and also a famous tradition of Greek philosophy. Philo lived in both of these worlds at once. He came from a wealthy and important Jewish family. His brother was one of the richest men in the city. Philo had a full Greek education. He read Plato, the Stoics, and other Greek thinkers closely. But he was also a devout Jew who knew the Hebrew scriptures well. He spent his life trying to bring these two traditions together. Most of what Philo wrote was about the first five books of the Bible, called the Torah. He read them mostly in Greek, in a translation called the Septuagint. He wrote long commentaries explaining their deeper meaning. We know one firm fact about his life. In the year 39 or 40 CE, he led a Jewish group from Alexandria to Rome. They went to ask the emperor Caligula to protect the Jews after violent attacks in their city. Philo wrote about this dangerous mission himself. The year of his death is not known exactly, but it was probably soon after.

Pāṇini was an ancient Indian grammarian whose work on the Sanskrit language is often described as one of the greatest intellectual achievements of the ancient world. Almost nothing is known about him as a person. Scholars usually place him in the fifth or fourth century BCE, though some argue for earlier dates. He is said to have come from Shalatula, a town in the region of Gandhara, which is now in north-west Pakistan near the Afghan border. This area was on the north-western edge of the Indian cultural world and close to routes that connected India with Persia, Central Asia, and the Mediterranean. A few traditional stories about his life exist, but they are legends rather than reliable history. What survives and matters is his book. It is called the Ashtadhyayi, which means the Eight Chapters, because it is divided into eight books. The book contains around four thousand short rules called sutras. These rules together describe the grammar of the Sanskrit language of his time with extraordinary completeness and precision. The sutras are not written for beginners. They are compressed to the point of being almost impossible to understand without training. Each sutra uses only the smallest number of syllables needed to state a rule. The rules also refer to each other in complex ways — later rules assume earlier rules, some rules override others in specific conditions, abbreviations are used to save space. Reading the Ashtadhyayi properly requires first learning Pāṇini's own system of notation. Later Indian grammarians spent the next two thousand years writing commentaries that explained his work. The most important of these was by Patanjali in the second century BCE. Modern scholars have continued to study the Ashtadhyayi and have discovered that it anticipates many features of modern linguistic and computer science theory. Pāṇini's grammar is one of the oldest works in any field that still rewards close study today.