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).

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.

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.

Karl Marx was born in the German city of Trier in 1818. He studied law in Bonn and Berlin at his father's insistence, but his true interests lay elsewhere and, in 1841, he received a doctorate in philosophy from the University of Jena.

For the next two years he wrote for radical left-wing newspapers before moving to Paris with his wife, Jenny; there he became a communist and met his lifelong friend and collaborator, Friedrich Engels.

They published their revolutionary pamphlet, The Communist Manifesto, in 1848 and Marx moved to London a year later. He spent the rest of his life there - often in considerable poverty - while he wrote his magnum opus of political theory, Das Kapital. Karl Marx died in 1883.

Rosa Luxemburg (1871-1919) was a Polish-born Jewish revolutionary and one of the greatest theoretical minds of the European socialist movement. An activist in Germany and Poland, the author of numerous classic works, she participated in the founding of the German Communist Party and the Spartacist insurrection in Berlin in 1919. She was assassinated in January of that year and has become a hero of socialist, communist and feminist movements around the world.

Peter Kropotkin (1842-1921) came from a major aristocratic Russian family but turned his back on it to embrace a life of imprisonment and exile in pursuit of his beliefs. His major works are The Conquest of Bread and Mutual Aid. His funeral was marked by the last permitted gathering of anarchists in the USSR.