Tools may be animate as well as inanimate; for instance, a ship's captain uses a lifeless rudder, but a living man for watch; for a servant is, from the point of view of his craft, categorized as one of its tools. So any piece of property can be regarded as a tool enabling a man to live, and his property is an assemblage of such tools; a slave is a sort of living piece of property; and like any other servant is a tool in charge of other tools.

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

Happiness may be defined as good fortune joined to virtue, or a independence, or as a life that is both agreeable and secure.

The chief forms of beauty are order and symmetry and definiteness, which the mathematical sciences demonstrate in a special degree.

All men, or most men, wish what is noble but choose what is profitable; and while it is noble to render a service not with an eye to receiving one in return, it is profitable to receive one. One ought therefore, if one can, to return the equivalent of services received, and to do so willingly; for one ought not to make a man one's friend if one is unwilling to return his favors.

That which is excellent endures.

The same ideas, one must believe, recur in men's minds not once or twice but again and again.