1. Man possesses two faculties which make up his life, one is called the will, the other the understanding. They are distinct, but so created as to make one, and when they are one they are called the mind. So the human mind consists of them, and there the whole of a person's life is in its beginnings, and this is the source from which it is present in the body.

2. Just as everything in the universe which is in due order has reference to good and truth, so everything in a person has reference to his will and understanding, for good in a person has to do with his will and truth to his understanding. For these two faculties, his twin lives, act as receivers and subjects upon which good and truth act. The will is the receiver for everything to do with good and the subject on which it acts; and the understanding is the receiver for everything to do with truth and the subject on which it acts. There is nowhere else in a person for the various kinds of good and truth; and since there is nowhere else in a person for them, nor is there therefore for love and faith, seeing that love belongs to good and good to love, and faith belongs to truth and truth to faith.

3. The will and the understanding also make up a person's spirit. For that is where his wisdom and intelligence reside, as also do his love and charity, and in general it is the seat of his life. The body is merely an obedient servant.

4. There is nothing it is more important to know than how the will and the understanding make up one mind. They do so, just as good and truth make one, for there is a marriage between the will and the understanding similar to that between good and truth, The facts about to be cited concerning good and truth will make clear what sort of a marriage that is; namely, that just as good is the very being (esse) of a thing, and truth is its coming-into-being (existere) as a result, so in a person his will is the very being of his life, and the understanding is the coming-into-being of his life as a result. For good belonging to the will takes on form in the understanding and becomes visible.

* 397-402 are repeated from HD 28-32, 11-19, 54-61, 55-78 and 36-46.