Knowledge in all things is knowing the ledge, a question of balancing of elements so that the metaphors used to describe each attempt at gaining this knowing-the-ledge through something as imprecise as human language become as close to the the FIRST metaphors triggered by nerve stimuli into image and sound and then concept, which started the whole process in childhood in the first place. The objective essence of things is a big mystery and cannot be fully known even through mathematics, since first you learn your metaphors and concepts and only afterwards mathematics or the laws of number and succession inherent in nature.
Physical beauty or the know-ledge of what FORMS are balanced enough to be "beautiful" is a question of proportion but the beauty of a person is not limited to just the physical realm. Physically ugly people, such as Frank Zappa and Mick Jagger, for instance, can become far more attractive than supermodels, when the more superiorly balanced and tempered elements of their personality or "artistic talent" nullify and override more superficial things such as a big schnozze or gigantic lips. Using the same logic, physically gorgeous people become quite unattractive to any person of intelligence when their personality, compassion, integrity and ego is out of proportion. In the artistic realm, temperance is not compromise is what the ancient Greeks taught more than 2000 years ago. The non-artist compromises his or her integrity and thinks its temperance whereas the real artist would rather burn the creation (as Frank Lloyd Wright threatened to do to one of his buildings, just like Howard Roark in "The Fountainhead," a character inspired by him) than compromise an inch, but he can temper every last detail of his work endlessly, making the work better and better each time. This is why you have musicians spending a year mixing an album. They want to be real artists and learn how to temper infinitely but this is one of the HARDEST things to learn. Making a true work of art is NOT easy. Thousands are pretentious enough to try it and then claim it and even be praised by even more pretentious "critics" for it, but few can really do it in a way that's universal enough to last centuries and millennia.
Fortunately we have invented plastic surgery for the physically challenged and head-shrinkers and gurus for the spiritually and personality challenged.