I am hoping that there is a Thomist here that could help me understand a doctrine of St. Thomas concerning the will.

Whether the will is of good only?

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On the contrary, Dionysius says (Div. Nom. iv) that "evil is outside the scope of the will," and that "all things desire good."

I answer that, The will is a rational appetite. Now every appetite is only of something good. The reason of this is that the appetite is nothing else than an inclination of a person desirous of a thing towards that thing. Now every inclination is to something like and suitable to the thing inclined. Since, therefore, everything, inasmuch as it is being and substance, is a good, it must needs be that every inclination is to something good. And hence it is that the Philosopher says (Ethic. i, 1) that "the good is that which all desire."

But it must be noted that, since every inclination results from a form, the natural appetite results from a form existing in the nature of things: while the sensitive appetite, as also the intellective or rational appetite, which we call the will, follows from an apprehended form. Therefore, just as the natural appetite tends to good existing in a thing; so the animal or voluntary appetite tends to a good which is apprehended. Consequently, in order that the will tend to anything, it is requisite, not that this be good in very truth, but that it be apprehended as good. Wherefore the Philosopher says (Phys. ii, 3) that "the end is a good, or an apparent good."

In every sin a privation of due order or conformity to the moral law is found, but sin is not a pure, or entire privation of all moral good (St. Thomas, "De malo", 2:9; I-II:73:2). There is a twofold privation; one entire which leaves nothing of its opposite, as for instance, darkness which leaves no light; another, not entire, which leaves something of the good to which it is opposed, as for instance, disease which does not entirely destroy the even balance of the bodily functions necessary for health. A pure or entire privation of good could occur in a moral act only on the supposition that the will could incline to evil as such for an object. This is impossible because evil as such is not contained within the scope of the adequate object of the will, which is good. The sinner's intention terminates at some object in which there is a participation of God's goodness, and this object is directly intended by him. The privation of due order, or the deformity, is not directly intended, but is accepted in as much as the sinner's desire tends to an object in which this want of conformity is involved, so that sin is not a pure privation, but a human act deprived of its due rectitude. From the defect arises the evil of the act, from the fact that it is voluntary, its imputability.

If my understanding of this is correct, and please inform me if it is not, the will only desires objects, and as all objects are good in and of themselves (as God has made them), the object of the will is always good. So, when we sin, it's not that we desire evil as such, but that our desiring of a good object unintentionally creates some deprivation or deformity; as when a man commits fornication with a woman, the woman whom he desired is herself a good object, but the deformity of unchastity that this act introduced to them both was not intentionally willed by the man, but was rather an unintended consequence.

Here's the problem I have. I agree that all objects in themselves are good, and that therefore one cannot will evil as an object since evil is no object, but I find that the will is not only concerned with objects, but with accidents of objects such as their relations and qualities and so on. So, while most men that commit fornication may not intend the deprivation of good called purity in the object of his lust, there are some men so depraved as to will directly and intentionally to cause impurity in others. It is the same with murder. In murder the object of the will is not a created (good) substance, but a change in the substance (the privation of life). So we can directly and intentionally will privations and deformities. Ultimately this will is not for any object but rather for the destruction of objects and their goodness, it is a lust for destruction. It is the desire to spread impurity in lust, the desire to spread death on murder, the desire for one's own death death in ѕυιcιdє, the desire to rid oneself of God's grace in pride, despair, and malice. In addition, I believe it's possible for men to know clearly in their minds that such a desire is evil, but to have the desire regardless.

What am I failing to understand here?