Sun Tzu is a honorific title bestowed upon Sūn Wu (c. 544-496 BC), the author of The Art of War, an immensely influential ancient Chinese book on military strategy.

He is also one of the earliest realists in international relations theory. In the author's name, Sūn Wu, the character wu, meaning "military", is the same as the character in wu shu, or martial art. Sun Wu also has a courtesy name, Chang Qing (Cháng Qīng).

Confucius (551-479 BCE) was born into a noble family in the Chinese state of Lu. His father died when he was very young and the family fell into poverty. Confucius resigned from a political career and then travelled for many years, searching for a province willing to adopt his ideas. Unsuccessful, he returned to Lu where he spent the rest of his life teaching. He is considered one of the most influential figures in the world.

Not much is known about the legendary LAO TZU, to whom authorship of the TAO TEH CHING is popularly attributed. Some scholars believe the author was an elder contemporary of Confucius.

Plato ranks among the most familiar ancient philosophers, along with his teacher, Socrates, and his student, Aristotle.

In addition to writing philosophical dialogues - used to teach logic, ethics, rhetoric, religion, and mathematics as well as philosophy - he founded Athens' Academy, the Western world's first institution of higher learning.

Aristotle was born in the Macedonian city of Stagira in 384 BC, and died in 322. He studied in Plato's Academy in Athens and later became tutor to Alexander the Great, before establishing his own school in Athens, called the Lyceum. His writings, which were of extraordinary range, profoundly affected the whole course of ancient, medieval and modern philosophy. Many of them have survived, including The Nicomachean Ethics, The Politics and Poetics, among others.

Marcus Aurelius Antoninus was born in AD 121, in the reign of the emperor Hadrian. At first he was called Marcus Annius Verus, but his well-born father died young and he was adopted, first by his grandfather, who had him educated by a number of excellent tutors, and then, when he was sixteen, by Aurelius Antoninus, his uncle by marriage, who had been adopted as Hadrian's heir, and had no surviving sons of his own. Aurelius Antoninus changed Marcus' name to his own and betrothed him to his daughter, Faustina. She bore fourteen children, but none of the sons survived Marcus except the worthless Commodus, who eventually succeeded Marcus as emperor.

On the death of Antoninus in 161, Marcus made Lucius Verus, another adopted son of his uncle, his colleague in government. There were thus two emperors ruling jointly for the first time in Roman history. The Empire then entered a period troubled by natural disasters, famine, plague and floods, and by invasions of barbarians. In 168, one year before the death of Verus left him in sole command, Marcus went to join his legions on the Danube.

Apart from a brief visit to Asia to crush the revolt of Avidius Cassius, whose followers he treated with clemency, Marcus stayed in the Danube region and consoled his somewhat melancholy life there by writing a series of reflections which he called simply To Himself. These are now known as his Meditations, and they reveal a mind of great humanity and natural humility, formed in the Stoic tradition, which has long been admired in the Christian world. He died, of an infectious disease, perhaps, in camp on 17 March AD 180.

Niccolò di Bernardo dei Machiavelli (3 May 1469 - 21 June 1527) was an Italian philosopher, humanist, and writer based in Florence during the Renaissance.

He is one of the main founders of modern political science. He was a diplomat, political philosopher, playwright, and a civil servant of the Florentine Republic. He also wrote comedies, carnival songs, poetry, and some of the most well-known personal correspondence in the Italian language.