It is impossible, or not easy, to alter by argument what has long been absorbed by habit

Every skill and every inquiry, and similarly every action and rational choice, is thought to aim at some good; and so the good had been aptly described as that at which everything aims.

The void is 'not-being,' and no part of 'what is' is a 'not-being,'; for what 'is' in the strict sense of the term is an absolute plenum. This plenum, however, is not 'one': on the contrary, it is a 'many' infinite in number and invisible owing to the minuteness of their bulk.

Any polis which is truly so called, and is not merely one in name, must devote itself to the end of encouraging goodness. Otherwise, political association sinks into a mere alliance.

Political society exists for the sake of noble actions, and not of mere companionship.

No great mind has ever existed without a touch of madness.

All men by nature desire to know. An indication of this is the delight we take in our senses; for even apart from their usefulness they are loved for themselves; and above all others the sense of sight. For not only with a view to action, but even when we are not going to do anything, we prefer seeing (one might say) to everything else. The reason is that this, most of all the senses, makes us know and brings to light many differences between things.

Every science seeks certain principles and causes for each of its objects—e.g. medicine and gymnastics and each of the other sciences, whether productive or mathematical. For each of these marks off a certain class of things for itself and busies itself about this as about something existing and real—not however qua real; the science that does this is another distinct from these.

The weak are always anxious for justice and equality. The strong pay no heed to either.