The purpose of external beauty is to remind us of the good and fair

"Now he whose vision of the mystery is long past, or whose purity has been sullied, cannot pass swiftly hence to see beauty's self yonder, when he beholds that which is called beautiful here; wherefore he looks upon it with no reverence." Plato, Phaedrus 250e


"When he that loves beauty is touched by such madness he is called a lover. Such a one, as soon as he beholds the beauty of this world, is reminded of true beauty, and his wings begin to grow; then is he fain to lift his wings and fly upward; yet he has not the power, but inasmuch as he gazes upward like a bird, and cares nothing for the world beneath, men charge it upon him that he is demented." Plato, Phaedrus, 249e

That high philosophy of Beauty which the ancient writers delighted in; for they said, that the soul of man, embodied here on earth, went roaming up and down in quest of that other world of its own, out of which it came into this, but was soon stupefied by the light of the natural sun, and unable to see any other objects than those of this world, which are but shadows of real things. Therefore, the Deity sends the glory of youth before the soul, that it may avail itself of beautiful bodies as aids to its recollection of the celestial good and fair.”
Ralph Waldo Emerson, Love

Why don’t we feel beauty intensely?

“In most of our lives there is a lack of sensitivity to beauty. You may see a beautiful face, a lovely painting, a marvelous temple and the sculptured hills, but never feel intensely or passionately the beauty of the earth and the sky. One wonders why.”

Beauty is boring

“Beauty is perfect, and perfection (such is human nature) holds our attention but for a little while. The mathematician who after seeing Phèdre asked: “Qu’est-ce que ça prouve?” was not such a fool as he was generally made out. No one has ever been able to explain why the Doric temple of Paestum is more beautiful than a glass of cold beer except by bringing in considerations that have nothing to do with beauty. Beauty is a blind alley. It is a mountain peak which once reached leads nowhere. That is why in the end we find more to entrance us in El Greco than in Titian, in the incomplete achievement of Shakespeare than in the consummate success of Racine. Too much has been written about beauty. That is why I have written a little more. Beauty is that which satisfies the aesthetic instinct. But who wants to be satisfied? It is only to the dullard that enough is as good as a feast. Let us face it: beauty is a bit of a bore.”
William Somerset Maugham, Cakes and Ale


The goal of culture should be not beauty but goodness
The value of culture is its effect on character. It avails nothing unless it ennobles and strengthens that. It's use is for life. It's aim is not beauty but goodness. Too often as we know, it gives rise to self-complacency. Who has not seen the scholar's thin-lipped smile when he corrects a misquotation, and the connoisseurs pained look when someone praises a picture he does not care for. There is no more merit in having read a thousand books than in having plowed a thousand fields. There is no more merit in being able to attach a correct description to a picture, than in being able to find out what is wrong with a stalled motorcar.
In each case it is special knowledge. The stockbroker has his knowledge too, and so has the artisan. It is a silly prejudice of the intellectual that his is the only one that counts. The True, the Good, and the Beautiful, are not the perquisites of those who have been to expensive schools, burrowed in libraries, and frequented museums. The artist has no excuse when he uses others with condescension. He is a fool if he thinks his knowledge is more important than theirs, and an oaf if he cannot comfortably meet them on equal footing.
W. Somerset Maugham, Chapter 24, The Summing Up, 2:33:15

Beauty is where God and the devil join battle

Beauty is a terrifying thing! It’s so frightening because it’s indefinable and it’s indefinable because God has surrounded us with nothing but riddles. Here the shores of a river meet, incompatibilities coexist. I am not an educated man, brother, but I have been thinking about this a great deal. There are so many mysteries; so many riddles that weigh man down to the ground. He is expected to solve them somehow or other and to climb dry out of the water. It’s beautiful, isn’t it? What I really can’t bear, though, is that a man with a noble heart and a superior intelligence may start out with the Madonna as his ideal and end up with Sodom as his ideal. It is even worse for one already striving for his Sodom ideal, who has not renounced his Madonna ideal, which still sets his heart ablaze, as it did when he was young and innocent. Yes, sir, a man’s range of feelings is wide, too wide even, and if I had my way, I’d narrow it quite a bit. It’s a hell of a situation, you know: what the head brands as shameful may appear as sheer beauty to the heart. But can there be beauty in Sodom? Yes and, believe me, it is precisely there that beauty lies for most men. Weren’t you aware of that secret