Hippocrates is an excellent geometer but a complete fool in everyday affairs.

The energy of the mind is the essence of life.

For knowing is spoken of in three ways: it may be either universal knowledge or knowledge proper to the matter in hand or actualising such knowledge; consequently three kinds of error also are possible.

Rhetoric may be defined as the faculty of observing in any given case the available means of persuasion.

But nothing is yet clear on the subject of the intellect and the contemplative faculty. However, it seems to be another kind of soul, and this alone admits of being separated, as that which is eternal from that which is perishable, while it is clear from these remarks that the other parts of the soul are not separable, as some assert them to be, though it is obvious that they are conceptually distinct.

A man is the origin of his action.

A great city is not to be confounded with a populous one.