That is the best part of beauty, which a picture cannot express; no, nor the first sight of the life. There is no excellent beauty, that hath not some strangeness in the proportion. A man cannot tell whether Apelles, or Albert Durer, were the more trifler; whereof the one, would make a personage by geometrical proportions; the other, by taking the best parts out of divers faces, to make one excellent. Such personages, I think, would please nobody, but the painter that made them. Not but I think a painter may make a better face than ever was; but he must do it by a kind of felicity (as a musician that maketh an excellent air in music), and not by rule. A man shall see faces, that if you examine them part by part, you shall find never a good; and yet altogether do well.

43 Of Beauty by Francis Bacon