Part IV. Of Human Bondage, or the Strength of the Emotions. Preface Human infirmity in moderating and checking the emotions I name bondage: for, when a man is a prey to his emotions, he is not his own master, but lies at the mercy of fortune: so much so, that he is often compelled, while seeing that which is better for him, to follow that which is worse. Why this is so, and what is good or evil in the emotions, I propose to show in this part of my treatise. But, before I begin, it would be well to make a few prefatory observations on perfection and imperfection, good and evil. When a man has purposed to make a given thing, and has brought it to perfection, his work will be pronounced perfect, not only by himself, but by everyone who rightly knows, or thinks that he knows, the intention and aim of its author. For instance, suppose anyone sees a work (which I assume to be not yet completed), and knows that the aim of the author of that work is to build a house, he will call the work imperfect ; he will, on the other hand, call it perfect, as soon as he sees that it is carried through to the end, which its author had purposed for it. But if a man sees a work, the like whereof he has never seen before, and if he knows not the intention of the artificer, he plainly cannot know, whether that work be perfect or imperfect. Such seems to be the primary meaning of these terms. But, after men began to form general ideas, to think out types of houses, buildings, towers, &c., and to prefer certain types to others, it came about, that each man called perfect that which he saw agree with the general idea he had formed of the thing in question, and called imperfect that which he saw agree less with his own preconceived type, even though it had evidently been completed in accordance with the idea of its artificer. This seems to be the only reason for calling natural phenomena, which, indeed, are not made with human hands, perfect or imperfect : for men are wont to form general ideas of things natural, no less than of things artificial, and such ideas they hold as types, believing that Nature (who they think does nothing without an object) has them in view, and has set them as types before herself. Therefore, when they behold something in Nature, which does not wholly conform to the preconceived type which they have formed of the thing in question, they say that Nature has fallen short or has blundered, and has left her work incomplete. Thus we see that men are wont to style natural phenomena perfect or imperfect rather from their own prejudices, than from true knowledge of what they pronounce upon. Now we showed in the Appendix to Part I., that Nature does not work with an end in view. For the eternal and infinite Being, which we call God or Nature, acts by the same necessity as that whereby it exists. For we have shown, that by the same necessity of its nature, whereby it exists, it likewise works (I. xvi.). The reason or cause why God or Nature exists, and the reason why he acts, are one and the same.