Morison, First principles of typography (1930):
Type design moves at the pace of the most conservative reader. The good type designer therefore realises that, for a new fount to be successful, it has to be so good that only very few recognise its novelty. If readers do not notice the consummate reticence and rare discipline of a new type, it is probably a good letter. But if my friends think that the tail of my lower-case r or the lip of my lower-case e is rather jolly, you may know that the fount would have been better had neither been made.