Nietzsche, "Beyond Good and Evil", 261

“Among the things which a noble human being perhaps finds hardest to understand is vanity: he will be tempted to deny its existence where a different type of human being will thing it palpably evident. For him the problem is to imagine creatures who try to awaken a good opinion of themselves which they themselves do not hold – and thus do not ‘deserve’ either – and yet subsequently come to believe this good opinion themselves. This seems to him in part so tasteless and lacking in self-respect and in part so baroquely irrational that he would prefer to consider vanity exceptional and in most cases where it is spoken of he doubts its existence…. The vain man takes pleasure in every good opinion he hears about himself (quite apart from any point of view of utility and likewise regardless of truth or falsehood), just as he suffers from every bad opinion: for he submits to both, he feels subject to them from that oldest instinct of subjection which breaks out in him. – It is ‘the slave# in the vain man’s blood, a remnant of the craftiness of the slave – and how much ‘slave’ still remains I woman, for example! – which seeks to seduce him to good opinions about himself; it is likewise the slave who immediately afterwards falls down before these opinions as if he himself had not called them forth. – And to say it again: vanity is an atavism.”