Virtue is uniform, conformable to reason, and of unvarying consistency; nothing can be added to it that can make it more than virtue; nothing can be taken from it, and the name of virtue be left.
The most evident difference between man and animals is this: the beast, in as much as it is largely motivated by the senses and with little perception of the past or future, lives only for the present. But man, because he is endowed with reason by which he is able to perceive relationships, sees the causes of things, understands the reciprocal nature of cause and effect, makes analogies, easily surveys the whole course of his life, and makes the necessary preparations for its conduct.
For while we are enclosed in these confinements of the body, we perform as a kind of duty the heavy task of necessity; for the soul from heaven has been cast down from its dwelling on high and sunk, as it were, into the earth, a place just the opposite to godlike nature and eternity. But I believe that the immortal gods have sown souls in human bodies so there might exist beings to guard the world and after contemplating the order of heaven, might imitate it by their moderation and steadfastness in life.
It is a strong proof of men knowing most things before birth, that when mere children they grasp innumerable facts with such speed as to show that they are not then taking them in for the first time, but are remembering and recalling them.