To leave the number of births unrestricted, as is done in most states, inevitably causes poverty among the citizens, and poverty produces crime and faction.

Why is it that all men who are outstanding in philosophy, poetry or the arts are melancholic?

These virtues are formed in man by his doing the actions ... The good of man is a working of the soul in the way of excellence in a complete life.

Good habits formed at youth make all the difference.

Where the laws are not supreme, there demagogues spring up.

It is clear, then, that the earth must be at the centre and immovable, not only for the reasons already given, but also because heavy bodies forcibly thrown quite straight upward return to the point from which they started, even if they are thrown to an infinite distance. From these considerations then it is clear that the earth does not move and does not lie elsewhere than at the centre.

If happiness, then, is activity expressing virtue, it is reasonable for it to express the supreme virtue, which will be the virtueof the best thing.