Again, the adversary may calumniate, saying that, although many desires are fulfilled in the acquisition of knowledge, the last is never attained, which is the imperfection of that one desire, which does not gain its end; and that will be both one and imperfect.
Again one here replies that it is not a truth which is brought forward in opposition, that is, that the last desire is never attained; for our natural desires, as is proved in the third treatise of this book, are all tending to a certain end; and the desire for knowledge is natural, so that this desire compasses a certain end, although but few, since they walk in the wrong path, accomplish the day’s journey. And he who understands the Commentator in the third chapter, On the Soul, learns this of him; and therefore Aristotle says, in the tenth chapter of the Ethics, against Simonides the Poet, that man ought to draw near to Divine things as much as is possible; wherein he shows that our power tends towards a certain end. And in the first book of the Ethics he says that the disciplined Mind demands certainty in its knowledge of things in proportion as their nature received certainty, in which he proves that not only on the side of the man desiring knowledge, but on the side of the desired object of knowledge, attention ought to be given; and therefore St. Paul says: “Not much knowledge, but right knowledge in moderation.” So that in whatever way the desire for knowledge is considered, either generally or particularly, it comes to perfection.
And since knowledge is a noble perfection, and through the desire for it its perfection is not lost, as is the case with the accursed riches, we must note briefly how injurious they are when possessed, and this is the third notice of their imperfection. It is possible to see that the possession of them is injurious for two reasons: one, that it is the cause of evil; the other, that it is the privation of good. It is the cause of evil, which makes the timid possessor wakeful, watchful, and suspicious or hateful.