The character Jubal Harshaw says this line in Stranger. Interestingly, in the "Uncut" version of the book, the character does not speak this line. Many argue that Harshaw is the true main character of the book, as he consistently proffers the philosophies another character must deal with.
The Little Book of Bathroom Philosophy : Daily Wisdom from the Greatest Thinkers (2004) by Gregory Bergman, p. 50
The original, full quote reads "Quantum in te crescit amor, tantum crescit pulchritudo; quia ipsa charitas est animae pulchritudo," and was fully translated as "Since love grows within you, so beauty grows. For love is the beauty of the soul." Here Augstine points out the inherent beauty that takes root within us when we love.
This quote is drawn from a novella that is the most widely translated book of its native language: French. The story tells of a narrator, a Prince, and a fox. The fox speaks this line to the little prince, after the prince tames the fox.
In what is perhaps Western society's most famous romance, this line is spoken by Juliet while standing on a balcony in what is perhaps the most famous scene of the play, wherein Romeo says, "But, soft! what lgith through yonder window breaks! It is the east, and Juliet is the sun!"