Prudence as well as Moral Virtue determines the complete performance of a man's proper function: Virtue ensures the rightness of the end we aim at, Prudence ensures the rightness of the means we adopt to gain that end.
For imitation is natural to man from his infancy. Man differs from other animals particularly in this, that he is imitative, and acquires his rudiments of knowledge in this way; besides, the delight in it is universal.
What is the highest of all goods achievable by action? ...both the general run of man and people of superior refinement say that it is happiness ...but with regard to what happiness is they differ.
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 has been well said that 'he who has never learned to obey cannot be a good commander.' The two are not the same, but the good citizen ought to be capable of both; he should know how to govern like a freeman, and how to obey like a freeman - these are the virtues of a citizen.
We are masters of our actions from the beginning up to the very end. But, in the case of our habits, we are only masters of their commencement - each particular little increase being as imperceptible as in the case of bodily infirmities. But yet our habits are voluntary, in that it was once in our power to adopt or not to adopt such or such a course of conduct.