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 the intention and aim of its authorand sees that it is carried through to the end. 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 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 perfect or imperfect: for men are wont to form general ideas of things natural believing that Nature (who they think does nothing without an object) has them in view. Men are wont to style natural phenomena perfect or imperfect rather from their own prejudices, than from true knowledge.
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... The reason or cause why God or Nature exists, and the reason why he acts, are one and the same. Therefore, as he does not exist for the sake of an end, so neither does he act for the sake of an end; of his existence and of his action there is neither origin nor end.
Spinoza begins Part IV of his book with a lengthy preface. The first sentence pronounces that human beings are slaves to their emotions. Why this is and what in the emotions is good and bad is to be the theme of this part. But first some things need to be made clear.
A thing is called perfect by men if it carrries out the intention of its maker. If the intention is not known the finished product can neither named perfect or imperfect. But men form general ideas about things and make pronouncements of perfect or imperfect based their own preconceptions.
Men think that Nature does things as if it had a purpose and then they judge natural phenomena as perfect or imperfect based on those preconceptions. For Spinoza Nature is purposeless, acting only through its own unchangeable laws therefore its products are perfect - the way they had to be. This is a far reaching doctrine, for by it a tree is without purpose, the universe is without purpose - it just is.
Does it mean that a man is without purpose? Assuredly not, he makes his own and, as we shall see, can find happiness in working within it.