To love is good, too: love being difficult. For one human being to love another: that is perhaps the most difficult of all our tasks, the ultimate, the last test and proof, the work for which all other work is but preparation...Love is a high inducement to the individual to ripen, to become something in himself, to become world for himself for another's sake, it is a great exacting claim upon him, something that chooses him out and calls him to vast things.