Man doeth this and doeth that from the good or evil of his heart; but he knows not to what end his sense doth prompt him; for when he strikes he is blind to where the blow shall fall, nor can he count the airy threads that weave the web of circumstance. Good and evil, love and hate, night and day, sweet and bitter, man and woman, heaven above and the earth beneath--all those things are needful, one to the other, and who knows the end of each?