They are, as I have often said already, conscious of their own actions and appetites, but ignorant of the causes whereby they are determined to any particular desire. Therefore, the common saying that Nature sometimes falls short, or blunders, and produces things which are imperfect, I set down among the glosses treated of in the Appendix to Part 1. Perfection and imperfection, then, are in reality merely modes of thinking, or notions which we form from a comparison among one another of individuals of the same species; hence I said above (II:Def.vi.), that by reality and perfection I mean the same thing.
For we are wont to refer all the individual things in nature to one genus, which is called the highest genus, namely, to the category of Being, whereto absolutely all individuals in nature belong. Thus, in so far as we refer the individuals in nature to this category, and comparing them one with another, find that some possess more of being or reality than others, we, to this extent, say that some are more perfect than others. Again, in so far as we attribute to them anything implying negation - as term, end, infirmity, etc., we, to this extent, call them imperfect, because they do not affect our mind so much as the things which we call perfect, not because they have any intrinsic deficiency, or because Nature has blundered. For nothing lies within the scope of a thing's nature, save that which follows from the necessity of the nature of its efficient cause, and whatsoever follows from the necessity of the nature of its efficient cause necessarily comes to pass.
As for the terms good and bad, they indicate no positive quality in things regarded in themselves, but are merely modes of thinking, or notions which we form from the comparison of things one with another.
Thus one and the same thing can be at the same time good, bad, and indifferent. For instance, music is good for him that is melancholy, bad for him that mourns; for him that is deaf, it is neither good nor bad.
Nevertheless, though this be so, the terms should still be retained.
For, inasmuch as we desire to form an idea of man as a type of human nature which we may hold in view, it will be useful for us to retain the terms in question, in the sense I have indicated.
In what follows, then, I shall mean by, "good" that, which we certainly know to be a means of approaching more nearly to the type of human nature, which we have set before ourselves; by "bad," that which we certainly know to be a hindrance to us in approaching the said type. Again, we shall that men are more perfect, or more imperfect, in proportion as they approach more or less nearly to the said type.
For it must be specially remarked that, when I say that a man passes from a lesser to a greater perfection, or vice versa, I do not mean that he is changed from one essence or reality to another; for instance, a horse would be as completely destroyed by being changed into a man, as by being changed into an insect. What I mean is, that we conceive the thing's power of action, in so far as this is understood by its nature, to be increased or diminished. Lastly, by perfection in general I shall, as I have said, mean reality in other words, each thing's essence, in so far as it exists, and operates in a particular manner, and without paying any regard to its duration. For no given thing can be said to be more perfect, because it has passed a longer time in existence. The duration of things cannot be determined by their essence, for the essence of things involves no fixed and definite period of existence; but everything, whether it be more perfect or less perfect, will always be able to persist in existence with the same force wherewith it began to exist; wherefore, in this respect, all things are equal.
