The power by which individual things and, consequently, man preserve their being is the actual power of God or Nature, not in so far as it is infinite, but in so far as it can be manifested by the actual essence of man. The power therefore of man, in so far as it is manifested by his actual essence is part of the infinite power of God or Nature, that is to say, part of His essence. Again, if it were possible that man could suffer no changes but those which can be understood through his nature alone, it would follow that he could not perish, but that he would exist forever necessarily; and this necessary existence must result from a cause whose power is either finite or infinite, that is to say, either from the power of man alone, which would be able to place at a distance from himself all other changes which could take their origin from external causes, or it must result from the infinite power of Nature by which all individual things would be so directed that man could suffer no changes but those tending to his preservation. But the first case is absurd. The force by which man perseveres in existence is limited, and infinitely surpassed by the power of external causes. This is evident from the Axiom. Therefore if it were possible for a man to suffer no changes but those which could be understood through his own nature alone, and consequently (as we have shown) that he should always necessarily exist, this must follow from the infinite power of God; and therefore from the necessity of the divine nature, in so far as it is considered as affected by the idea of any one man, the whole order of Nature, in so far as it is conceived under the attributes of thought and extension, would have to be deduced. From this it would follow that man would be infinite, which (by the first part of this demonstration) is an absurdity. It is impossible, therefore, that a man can suffer no changes but those of which he is the adequate cause. Hence it follows that a man is necessarily always subject to passions, and that he follows and obeys the common order of Nature, accommodating himself to it as far as the nature of things requires. The force and increase of any passion and its perseverance in existence are not limited by the power by which we endeavor to persevere in existence, but by the power of an external cause compared with our own power. _The Nature of Good and Evil_