The strangeness in the proportion

 "There is no excellent beauty that hath not some strangeness in the proportion." 

Several decades ago, when I first saw that quote from Sir Francis Bacon in a pictoral collection in Readers Digest, it quickly became one of my favorites. By way of explanation, a face can be so perfect that it becomes almost uninteresting, whereas those with some slight defect by contrast become fascinating, or even hypnotic, and thus an "excellent" beauty.

An example might be the picture that I use for the character of Elliane McDermott in my Sir Cuthbert stories. In the first of the stories, Cuthbert Solves a Case, a friend asks Percy to tell her what it is that he doesn't like about her face, and he lists several supposed defects. She teases him that for someone who doesn't like her face he evidently has spent a good bit of time studying it. And defects they may justly have been, but he ends up marrying her anyway.