Aristotle left Athens and travelled for a time, and married, Pythias, the adoptive daughter of Hermias of Atarneus, in about 346 BC. He lived in Assos where he founded his first philosophical school. In 343 BC, family connections at the Macedonian court helped him to become appointed as the royal tutor by King Philip II. He therefore taught the king's son, Alexander the Great, who at the time was only 13 years-old. He also gave lessons to two other future kings: Ptolemy and Cassander as well as Hephaestion and Marsyas of Pella. (5)

There has been a great deal of speculation about the influence that Aristotle had on Alexander the Great. Bertrand Russell has argued: "As to Aristotle's influence on him (Alexander), we are left free to conjecture whatever seems to us most plausible. For my part, I should suppose it nil. Alexander was an ambitious and passionate boy, on bad terms with his father, and presumably impatient of schooling. Aristotle thought no State should have as many as one hundred thousand citizens, and preached the doctrine of the golden mean. I cannot imagine his pupil regarding him as anything but a prosy old pedant, set over him by his father to keep him out of mischief." (6)

In 335 BC he moved back to Athens where he established his own school there known as the Lyceum. It is claimed that Aristotle lectured to his chosen pupils in the mornings and to the general public in the evenings. The group of scholars who followed the Aristotelian doctrine came to be known as the Peripatetics due to Aristotle’s tendency to walk as he taught. Aristotle combined teaching and research and other men joined him in his scientific and philosophical enterprises. (7)

Aristotle and his students at the Lyceum did their best to collect, sort and explain the information that lay around them. In addition to their scientific work, they amassed the details of 158 political constitutions, made collections of barbarian customs and beliefs, compiled sporting almanacs, histories of philosophy and details of dramatic and musical performances. Aristotle also collected books, maps and biological specimens. (8)

It is claimed during this period that Aristotle developed very strong views on education. This is reflected in the comment: "The educated differ from the uneducated as much as the living from the dead." In Metaphysics he argued: "It is the mark of an educated mind to be able to entertain a thought without accepting it." (9) On another occasion he said: “Teachers who educated children deserved more honour than parents who merely gave them birth; for bare life is furnished by the one, the other ensures a good life”. (10) Aristotle encouraged his students to strive for refinement of character and the development of moral virtues, and to be equipped to make "a noble use of leisure". (11)

Aristotle’s main focus as a teacher was cooperative research, an idea which he founded through his natural history work and systematic collection of philosophical works to contribute to his library. His students were assigned historical or scientific research projects as part of their studies. Over the next few years with the help of his students produced a large number of manuscripts, "which, taken together and published in the modern style, would amount to perhaps fifty substantial volumes of print". Some of the material that has survived appear to be lecture notes. There are works on logic, language, the arts, ethics, politics, law, constitutional history, intellectual history, psychology, sociology, physiology, zoology, physics, biology, botany, chemistry, astronomy, mechanics, mathematics, philosophy, metaphysics and the theory of knowledge. (12)

Anthony Gottlieb, the author of The Dream of Reason: A History of Philosophy from the Greeks to the Renaissance (2000) has pointed out: "If Aristotle had never existed, it would be pointless to try and invent him. Nobody would believe that there could have been such a man... His surviving works run to almost one and a half million words. There is good reason to think that this is no more than a quarter of what he wrote; all of his works that were polished for publication have been lost, including several dialogues in the style of Plato. But what is left today is more than enough to put him in a class of his own. Any credible description of the impressiveness of his work would be an understatement." (13)

It has been pointed out that he had a different style of writing from his predecessors. "He is the first to write like a professor: his treatises are systematic, his discussions are divided into heads, he is a professional teacher, not an inspired prophet. His work is critical, careful, pedestrian, without any trace of Bacchic enthusiasm. The Orphic elements in Plato are watered down in Aristotle, and mixed with a strong dose of common sense; where he is Platonic, one feels that his natural temperament has been overpowered by the teaching to which he has been subjected. He is not passionate, or in any profound sense religious. The errors of his predecessors were the glorious errors of youth attempting the impossible; his errors are those of age which cannot free itself of habitual prejudices. He is best in detail and in criticism; he fails in large construction." (14)

It is believed that Aristotle began collecting information on animals in Assos and Lesbos. This pioneering work of zoology eventually appeared in his book, History of Animals (a better translation of the title would be Zoological Researches). Aristotle begins with men, because men are most familiar, and can be used as a reference point. "First, let us consider the parts of men; for just as people test currency by referring it to the standard most familiar to them, so it is in other cases too - and men are of necessity the sort of animal most familiar to us. Now the parts of men are clear enough to perception; nevertheless, in order that we may not break the proper sequence, and in order that we may rely on reason as well as perception, we must describe their parts - first the organic parts, then the uniform parts. Now the chief parts into which the body as a whole divides are these: head, neck, torso, two arms, two legs." (15)

Aristotle discusses in detail the different parts of animals, both external and internal. The blood, bone, hair, and the rest of which animals are constructed. He also writes about the various modes of reproduction found among animals; their diet, habitat, and behaviour. "Aristotle talks of sheep, goats, deer, pigs, lions, hyenas, elephants, camels, mice, mules. He describes swallows, pigeons, quails, woodpeckers, eagles, crows, blackbirds, cuckoos. His researches cover tortoises and lizards, crocodiles and vipers, porpoises and whales. He goes through the kinds of insect. And he is particularly informed and particularly informative about marine animals - fish, crustacea, cephalopods, testacea... Every species of animal known to the Greeks is noticed; most species are given detailed descriptions; in some cases Aristotle's accounts are both long and accurate." (16)

For example, here is part of his description of an octopus: "The octopus uses its tentacles both as feet and as hands: it draws in food with the two that are placed over its mouth; and the last of its tentacles, which is very pointed and the only one of them which is whitish and bifurcated at the tip (it uncoils towards the rhachis - the rhachis is the smooth surface on the opposite side from the suckers) - this it uses for copulation. In front of the sac and above the tentacles it has a hollow tube by which it discharges the sea-water which gets into the sac whenever it takes anything in with its mouth. It moves this tube to right and to left; and it discharges milt through it. It swims obliquely in the direction of the so-called head, stretching out its feet; and when it swims in this way it can see forwards (since its eyes are on top) and has its mouth at the rear. As long as the animal is alive, its head is hard and as it were inflated. It grasps and retains things with the underside of its tentacles, and the membrane between its feet is fully extended. If it gets on to the sand, it can no longer retain its hold." (17)

For over a thousand years universities used the published work of Aristotle. In 1641 René Descartes wrote privately to a friend, Marin Mersenne: "I may tell you, between ourselves, that these six Meditations contain all the foundations of my physics. But please do not tell people, for that might make it harder for supporters of Aristotle to approve them. I hope that readers will gradually get used to my principles, and recognize their truth, before they notice that they destroy the principles of Aristotle." (18)

In 1662 John Dryden became a member of the Royal Society, one the earliest of the European organizations dedicated to clearing away Aristotelian scholasticism and furthering new knowledge, wrote a poem about Aristotle that included the following lines: "The longest tyranny that every swayed/Was that wherein our ancestors betrayed/Their free-born reason to the Stagirite (Aristotle),/And made his torch their universal light/So truth, while only one supplied the State/Grew scarce, and dear and yet sophisticate." (19)

It has been pointed out that Aristotle and his researchers often made errors of a crude and unscientific kind. The observations he reports are, most of them, amateur; they were made in the open and not in the laboratory. There is no evidence that Aristotle ever attempted to establish correct experimental conditions or to make controlled observations; there is no evidence that he tried to repeat his observation, to check them or to verify them. "Finally, Aristotle is criticised for ignoring the importance of measurement. Real science is essentially quantitative, but Aristotle's descriptions are mostly qualitative... He had no notion of applying mathematics to zoology. He did not weigh and measure his specimens. He records a layman's impression of how things look rather than a professional's accurate description of how they are." (20)

Francis Bacon became one of Aristotle's fiercest critics and a rallying point for the scientific revolutionaries. It was "Aristotle's chemistry, physics and cosmology that fell loudest and hardest in the seventeenth century, to the blows of men" such as Galileo Galilei and Robert Boyle. "Aristotle's science, except for his biology, was condemned as not just barking up the wrong tree but lost in the wrong forest. So indeed it was. But plenty of the seventeenth century's anti-Aristotelian invective unfairly branded him with the sins of his slavish and inferior followers." (21)

In philosophy ethics is the study of concepts such as good, right, evil, wrong, moral obligation, duty and of the kinds of reasoning used in working out what one should do in given circumstances, and more generally how one should live or what kind of life is best. Its systematic inception is generally attributed to Socrates, who sought to encourage his contemporaries to pay attention to the question of how they should live. Plato suggested that Socrates urged self-understanding and the achievement of harmony in the soul as the basis of the well-lived life. (22)

Aristotle took a different view and identified "practical wisdom" as the means by which people could identify the middle path between extremes of vice as the proper route through life. Aristotle developed the theory of the "golden mean". Every virtue is a mean between two extremes, each of which is a vice. "Courage is a mean between cowardice and rashness; liberality, between prodigality and meanness; proper pride, between vanity and humility; ready wit, between buffoonery and boorishness; modesty, between bashfulness and shamelessness. Some virtues do not seem to fit into this scheme; for instance, truthfulness. Aristotle says that this is a mean between boastfulness and mock-modesty, but this only applies to truthfulness about oneself." (23)

The great work in which Aristotle set out his ethical views is the Nicomachean Ethics, so called because it was edited from his lecture notes by his son Nichomachus. It has a chapter in it on friendship. Aristotle thought friendship to be the highest and best of all human relationships. A friend, he said, is another self, so that his interests will be as one's own interests, and his fortunes as one's own. Friendship requires generosity, tolerance and understanding. According to Aristotle friends are desirable, for the happy man needs friends with whom to share his happiness. "No one would choose the whole world on condition of being alone, since man is a political creature and one whose nature is to live with others." (24)

Aristotle attempted to justify the institution of slavery. This was a subject that other Greek philosophers accepted as an inevitable fact of life and mostly passed over without comment. Anthony Gottlieb has argued: "If the moral philosophy of Socrates and Plato may be compared to trying to rewrite some of the rules of a club, Aristotle was more concerned to shed light on the club's existing constitution, and to see how the members could best be made to behave in accordance with it. Aristotle accepted that old rules "ought not always to remain unaltered" but change must be made very cautiously, because "a readiness to change from old to new laws enfeebles the power of the law." (25)

Whereas today we think that human beings all have equal rights, and that justice involves equality. However, Aristotle thinks that justice involves, not equality, but right proportion, which is only sometimes equality. The justice of a master or a father is a different thing from that of a citizen, for a son or slave. It is impossible for a man to be a friend of his slave: "There is nothing in common between the two parties; the slave is a living tool... A slave, then, one cannot be friends with him." (26)

A father can repudiate his son if he is wicked, but a son cannot repudiate his father, because he owes him more than he can possibly repay, especially existence. In unequal relations, it is right, since everybody should be loved in proportion to his worth, that the inferior should love the superior more than the superior loves the inferior: wives, children, subjects, should have more love for husbands, parents, and monarchs than the latter have for them. In a good marriage, "the man rules in accordance with his worth, and in those matters in which a man should rule, but the matters that befit a woman he hands over to her." He should not rule in her province; still less should she rule in his. (27)

Aristotle considers ethics a branch of politics and should help inform the structure of government. Rulers should be magnanimous. "The magnanimous man, since he deserves most, must be good, in the highest degree; for the better man always deserves more, and the best man most. Therefore the truly magnanimous man must be good. And greatness in every virtue would seem to be characteristic of the magnanimous man." Aristotle argues that monarchy is the best form of government, and aristocracy the next best. Monarchs and aristocrats can be "magnanimous", but ordinary citizens cannot. (28)

Alexander the Great died in June 323 BC. Aristotle feared that this would put him in danger and in 322 BC he retired to the island of Euboea. He died soon afterwards aged 62.

The Middle Ages

The Normans

The Tudors

The English Civil War

Industrial Revolution

First World War

Russian Revolution

Nazi Germany

United States: 1920-1945

(1) Georgios Anagnostopoulos, A Companion to Aristotle (2013) page 4

(2) Jonathan Barnes, Aristotle (2000) page 1

(3) Jostein Gaarder, Sophie's World (1995) page 70

(4) Anthony Gottlieb, The Dream of Reason: A History of Philosophy from the Greeks to the Renaissance (2000) page 227

(5) Peter Green, Alexander of Macedon (1991) pages 58-59

(6) Bertrand Russell, History of Western Philosophy (1946) page 174

(7) Jonathan Barnes, Aristotle (2000) page 9

(8) Anthony Gottlieb, The Dream of Reason: A History of Philosophy from the Greeks to the Renaissance (2000) page 233

(9) Aristotle, Metaphysics (c. 350 BC)

(10) Diogenes Laertius, Lives of Eminent Philosophers (1942 edition) page 463

(11) Anthony Grayling, Ideas that Matter (2009) page 153

(12) Jonathan Barnes, Greek Philosophers (1998) pages 196-197

(13) Anthony Gottlieb, The Dream of Reason: A History of Philosophy from the Greeks to the Renaissance (2000) page 220

(14) Bertrand Russell, History of Western Philosophy (1946) pages 174-175

(15) Aristotle, History of Animals (c. 340 BC)

(16) Jonathan Barnes, Aristotle (2000) page 18

(17) Aristotle, History of Animals (c. 340 BC)

(18) René Descartes, letter to Marin Mersenne (28th January 1641)

(19) John Dryden, To Dr Charleton (1662)

(20) Jonathan Barnes, Greek Philosophers (1998) page 208

(21) Anthony Gottlieb, The Dream of Reason: A History of Philosophy from the Greeks to the Renaissance (2000) page 223

(22) Anthony Grayling, Ideas that Matter (2009) page 180

(23) Bertrand Russell, History of Western Philosophy (1946) page 186

(24) Aristotle, Nicomachean Ethics (c. 340 BC)

(25) Anthony Gottlieb, The Dream of Reason: A History of Philosophy from the Greeks to the Renaissance (2000) page 265

(26) Aristotle, Nicomachean Ethics (c. 340 BC)

(27) Bertrand Russell, History of Western Philosophy (1946) pages 186-187

(28) Aristotle, Nicomachean Ethics (c. 340 BC)