Everyone knows of the existence of the will and the intellect. For in speaking he says 'I want this' and 'I understand this.' Yet he fails to keep them apart and treats them as identical. The reason is that he only reflects on what is to do with thought coming from the intellect, not on what is to do with love coming from the will, since this is not visible in such bright light as the other. Yet someone who fails to distinguish between will and intellect is unable to distinguish evil from good, so that he cannot know anything about the blame incurred by sin. But is there anyone who does not know that good and truth are two different things, just as love and wisdom are? Can anyone fail to conclude by the light of his reason that a person has two faculties, which separately receive and latch on to these, one being the will, the other the intellect? Because what the will receives and reproduces we call good, and what the intellect receives we call truth. For what the will loves and does is called good, and what the intellect perceives and thinks is called truth.

[2] In the first part of this book we spoke about the marriage of good and truth, and also had much to say about the will and the intellect and the various attributes and qualities of each. (It is my belief that these can be perceived even by those who have no distinct notion of the intellect and the will, for human reason is such as to be able to understand truths by their own light, even if it had not previously distinguished them.) I shall therefore make some remarks to render clearer the distinction between the will and the intellect, with the intention of making known first the nature of acts of adultery by the reason or the intellect, and then by the will.

[3] The following points may serve to make these known. (a) The will alone does nothing of its own accord, but everything it does is done by means of the intellect. (b) Again, the intellect alone does nothing of its own accord, but everything it does is done at the instigation of the will. (c) The will influences the intellect, but the intellect does not influence the will; but the intellect lays down what is good and what is evil, and advises the will to choose from these two and to do what it pleases. (d) Following this they become linked in two ways. In one the will acts from within and the intellect from without; in the other the intellect acts from within and the will from without. This is what makes the difference between adultery of the reason, the subject of this section, and adultery of the will, which will be treated next. They need to be kept apart, because one is more serious than the other. For adultery of the reason is less serious than that of the will. This is because in adultery of the reason the intellect acts from within and the will from without; but in adultery of the will the will acts from within and the intellect from without. The will is the real person, and the intellect is made a person by the will; and that which acts from within has power over that which acts from without.