Happiness of any given life is to be measured, not by its joys and pleasures, but by the extent to which it has been free from suffering-from positive evil.
It is salutary for us to learn to hold cheap such things, be they good or evil, as attach indifferently to good men and bad, and to covet those good things which belong only to good men, and flee those evils which belong only to evil men.
So far as we are human, what we do must be either evil or good: so far as we do evil or good, we are human: and it is better, in a paradoxical way, to do evil than to do nothing: at least we exist.
We can never lose what is really ours. Who can lose his being? Who can lose his very existence? If I am good, it is the existence first, and then that becomes colored with the quality of goodness. If I am evil, it is the existence first, and that becomes colored with the quality of badness. That existence is first, last, and always; it is never lost but ever present.
Of all evil I deem you capable: Therefore I want good from you. Verily, I have often laughed at the weaklings who thought themselves good because they had no claws.
Evil had to manifest itself and fulfill its role, so that ultimately Good could prevail. [...] Evil needs to manifest itself, for them to understand the value of Good.
All Nature is but art, unknown to thee All chance, direction, which thou canst not see; All discord, harmony not understood; All partial evil, universal good.