Who Was Aristotle? The Man Who Tried to Organise Everything

Born in 384 BC in Stagira in northern Greece, the son of a physician to the Macedonian court, he went to Athens at seventeen and spent twenty years in Plato's Academy, first as a student and then as a member, leaving on Plato's death in 347. He spent the next dozen years travelling in Asia Minor and on Lesbos, where he did the marine biology that is among his best work, and then accepted an invitation from Philip of Macedon to tutor his son, the future Alexander. In 335 he returned to Athens and founded his own school, the Lyceum, teaching there for twelve years while assembling what appears to have been the first substantial research library and directing collaborative projects, including a survey of the constitutions of 158 city-states. Anti-Macedonian feeling after Alexander's death in 323 made Athens unsafe, and he left, reportedly saying he would not let the city sin twice against philosophy, a reference to the execution of Socrates. He died the following year.

His central break with his teacher is about where reality is located. Plato held that the world we perceive is an imperfect shadow of eternal Forms existing separately, so that a particular horse is a poor copy of the Form of Horse, and knowledge means turning away from the senses towards those Forms. Aristotle rejected the separation. For him the form of a thing is in the thing, inseparable from the matter that embodies it, and the way to understand horses is to look at horses. This is why he dissected animals, collected constitutions, catalogued rhetorical devices and analysed actual tragedies, and why his method looks so much more like science than his teacher's does. The famous fresco in which Plato points upward and Aristotle gestures out across the world is a fair summary of a real disagreement.

The range is the point, and several of these were fields that did not exist before him:

• •Logic: the syllogism, the first formal system of valid inference, which stood essentially unchanged as the whole of logic for over two thousand years until the nineteenth century
• •Biology: descriptions of about five hundred species, dissections, and observations so careful that some were disbelieved until confirmed in the nineteenth century, including the reproductive habits of a certain octopus and the placenta-like structure in a species of shark
• •Ethics: an account built not on rules but on character, in which the good life consists in flourishing through the exercise of virtues, each a mean between two extremes, developed by habit rather than taught
• •Politics: a comparative study of constitutions, the classification of regimes, and the claim that a human being is by nature an animal that lives in a city
• •Physics and cosmology: a complete account of motion, the four elements, and a universe of nested spheres with an unmoved mover at the outside, which was wrong and internally coherent enough to be very hard to dislodge
• •Poetics and rhetoric: the analysis of tragedy, plot, character and persuasion that still underlies most teaching on both

His physics is the clearest case of influence outliving correctness. He held that heavier bodies fall faster, that motion requires a continuously applied cause, that a vacuum is impossible, and that the heavens are made of a fifth element and move in perfect circles, none of which survives. In biology he thought the brain cooled the blood and the heart did the thinking. The reason these persisted was not stupidity but coherence: the system explained ordinary experience well, since a cart does stop when you stop pushing, and it was adopted wholesale by medieval universities and fused with Christian theology by Thomas Aquinas in the thirteenth century, so that questioning the physics touched the theology. Galileo's work on falling bodies and inertia is aimed directly at this system, and the scientific revolution is in large part the process of dismantling it.

What survives is peculiar. The polished dialogues he published in his lifetime, which Cicero admired for their style, are lost almost entirely; what we have are the working documents of the Lyceum, lecture notes and treatises compressed, repetitive and clearly not written for publication, which is why reading him is such hard going compared with Plato. These texts largely disappeared from western Europe after the fall of Rome and were preserved, translated and extensively developed in the Islamic world, where Ibn Sina and Ibn Rushd wrote commentaries that shaped the reception of the work for centuries. They returned to Europe from the twelfth century through translations from Arabic and Greek made in Spain and Sicily, arrived in the new universities, and dominated them so completely that a scholar could settle a question by citing him. Modern philosophy begins partly as a reaction against that authority, and yet virtue ethics is a live position again, his biology is admired in detail, and the vocabulary of substance, essence, potential, category and premise is still his.

Plato's pupil for twenty years and Alexander's tutor, he founded the Lyceum in Athens and produced the first systematic treatment of logic, biology, ethics, politics, rhetoric and literary criticism, breaking with his teacher by insisting that the form of a thing is in the thing and must be studied by observation. His syllogistic logic stood for two thousand years and his physics, coherent and wrong, took the scientific revolution to dismantle. The surviving texts are lecture notes, preserved and developed in the Islamic world before returning to Europe in the twelfth century.