To Unlearn is as hard as to Learn

We ought not to listen to those who exhort us, because we are human, to think of human things....We ought rather to take on immortality as much as possible, and do all that we can to live in accordance with the highest element within us; for even if its bulk is small, in its power and value it far exceeds everything.

In part, art completes what nature cannot elaborate; and in part it imitates nature.

The proof that you know something is that you are able to teach it

Those who assert that the mathematical sciences say nothing of the beautiful or the good are in error. For these sciences say and prove a great deal about them; if they do not expressly mention them, but prove attributes which are their results or definitions, it is not true that they tell us nothing about them. The chief forms of beauty are order and symmetry and definiteness, which the mathematical sciences demonstrate in a special degree.

Happiness, then, is co-extensive with contemplation, and the more people contemplate, the happier they are; not incidentally, but in virtue of their contemplation, because it is in itself precious. Thus happiness is a form of contemplation.

The moral virtues, then, are produced in us neither by nature nor against nature. Nature, indeed, prepares in us the ground for their reception, but their complete formation is the product of habit.