Thus the natural right of every man is determined not by sound reason, but by his desire and his power. For not all men are naturally determined to act in accordance with the rules and laws of reason. On the contrary, all men are born in a state of complete ignorance, and before they can learn the true way of life and acquire a virtuous disposition, even if they have been well brought up, a great part of their life has gone by. Yet in the meantime they have to live and preserve themselves as far as in them lies, namely, by the urging of appetite alone, for Nature has given them nothing else and has denied them the actualized power to live according to sound reason. Therefore they are no more in duty bound to live according to the laws of a sound mind than a cat to live according to the laws of a lion’s nature. Thus whatever every man, when he is considered as solely under the dominion of Nature, believes to be to his advantage, whether under the guidance of sound reason or under passion’s sway, he may by sovereign natural right seek and get for himself by any means, by force, deceit, entreaty or in any other way he best can, and he may consequently regard as his enemy anyone who tries to hinder him from getting what he wants.
From this it follows that Nature’s right and her established order, under which all men are born and for the most part live, forbids only those things that no one desires and no one can do; it does not frown on strife, or hatred, or anger, or deceit, or on anything at all urged by appetite. This is not surprising, for Nature’s bounds are not set by the laws of human reason which aim only at man’s true interest and his preservation, but by infinite other laws which have regard to the eternal order of the whole of Nature, of which man is but a particle. It is from the necessity of this order alone that all individual things are determined to exist and to act in a definite way. So when something in Nature appears to us as ridiculous, absurd or evil, this is due to the fact that our knowledge is only partial, that we are largely ignorant of the order and coherence of the whole of Nature and want all things to be arranged to suit our reason. Yet that which our reason declares to be evil is not evil in respect of the order and laws of universal Nature, but only in respect of the laws of our own nature.
Spinoza – from the Theological-Political Treatise Chapter 16