1. Studying the origin of evils that might affect all beings in general, or some one class in particular, it is reasonable to begin by defining evil, from a consideration of its nature. That would be the best way to discover whence it arises, where it resides, to whom it may happen, and in general to decide if it be something real. Which one of our faculties then can inform us of the nature of evil? This question is not easy to solve, because there must be an analogy between the knower and the known.[157] The Intelligence and the Soul may indeed cognize forms and fix their desires on them, because they themselves are forms; but evil, which consists in the absence of all goods, could not be described as a form.[158] But inasmuch as there can be but one single science, to embrace even contraries, and as the evil is the contrary of the good, knowledge of the good implies that of evil. Therefore, to determine the nature of evil, we shall first have to determine that of good, for the higher things must precede the lower, as some are forms and others are not, being rather a privation of the good. Just in what sense evil is the contrary of the good must also be determined; as for instance, if the One be the first, and matter the last;[159] or whether the One be form, and matter be its absence. Of this further.[160] A. PRIMARY AND SECONDARY EVIL. A DEFINITION OF EVIL BY CONTRAST WITH THE GOOD. 2. Let us now determine the nature of the Good, at least so far as is demanded by the present discussion. The Good is the principle on which all depends, to which everything aspires, from which everything issues, and of which everything has need. As to Him, He suffices to himself, being complete, so He stands in need of nothing; He is the measure[161] and the end of all things; and from Him spring intelligence, being, soul, life, and intellectual contemplation. NATURE OF DIVINE INTELLIGENCE.