'I surpass you', he said, 'in the explanation of phenomena, which is the principal mark of a good system. But, in my opinion, it is not a very good explanation of a phenomenon to assign to it an ad hoc principle: to evil, a principium maleficum, to cold, a primum frigidum; there is nothing so easy and nothing so dull.
The explanation of the cause of evil by a particular principle, per principium maleficum, is of the same nature. Evil needs no such explanation, any more than do cold and darkness: there is neither primum frigidum nor principle of darkness. Evil itself comes only from privation; the positive enters therein only by concomitance, as the active enters by concomitance into cold.