Any change of government which has to be introduced should be one which men, starting from their existing constitutions, will be both willing and able to adopt, since there is quite as much trouble in the reformation of an old constitution as in the establishment of a new one, just as to unlearn is as hard as to learn.

Neither by nature, then, nor contrary to nature do the virtues arise in us; rather we are adapted by nature to receive them, and are made perfect by habit.

The body is at its best between the ages of thirty and thirty-five.

The continuum is that which is divisible into indivisibles that are infinitely divisible.

Our youth should also be educated with music and physical education.

Wonder implies the desire to learn.

The best friend is he that, when he wishes a person's good, wishes it for that person's own sake.