The Explanation of Evil . . .
1. Evil is a necessary condition of free will. A world without possible evil consequences would be a world of clockwork dolls, not of men.
2. If a universe is to exist at all with time and force and change in it, the universe we have is the best balance of all those elements, "the best of possible worlds."
3. Evil properly understood is not an existing thing to be accounted for, but the absence of a possible good. In questioning evil we are really asking for a world statically perfect, whereas we live in a world that moves toward perfection.
4. Life means change, is in fact change. Change is from one condition to another. Comparison of earlier and later conditions causes the contrasts that we call good and evil. But absence of change would mean death or non-existence.
5. The universe, with all it contains, is neither evil nor good. What man makes of it by free choice creates evil. Iron can indifferently be a plow or a sword.
6. The good man is the crown of existence, and in a world without difficulties the good man could not occur.
7. Evil is only what man takes to be evil. It is the shadow cast by desire. Remove desire from the mortal, the fleeting, and the unobtainable, and evil vanishes.
8. Every wicked man has done some good things. Every good man has sinned. In this world each one is requited for the smaller side of his balance. He comes to the hereafter with a clear account of wickedness to be punished or virtue to be rewarded.
--Herman Wouk, Here Is My God, pp. 136-137