“Whence arises all that order and beauty we see in the world?”

A quel pietoso fonte, onde siam tutti,
S'assembra ogni beltà che qua si vede,
Più c'altra cosa alle persone accorte;
from sonnet "Veggio nel tuo bel viso, Signor mio"
Translated by Luciano Rebay, Invitation to Italian Poetry http://books.google.com/books?id=zAnjAbsgY0gC&pg=PA77 (1969), p. 77
Variant translations:
To those who are wise, nothing more resembles that merciful spring whence all derive than every beauty to be found here;
Translated by Christopher Ryan, The poetry of Michelangelo: An Introduction http://books.google.com/books?id=Iot1KpxQJpsC&pg=PA103 (1988), p. 103
Every beauty which is seen here below by persons of perception resembles more than anything else that celestial source from which we all are come.

As rendered by T. Byrom (1993), Shambhala Publications.
There is no quote from the Pali Canon that matches up with any of these. The closest quote to this is in the Majjhima Nikaya 19:
"Whatever a monk keeps pursuing with his thinking & pondering, that becomes the inclination of his awareness. If a monk keeps pursuing thinking imbued with sensuality, abandoning thinking imbued with renunciation, his mind is bent by that thinking imbued with sensuality. If a monk keeps pursuing thinking imbued with ill will, abandoning thinking imbued with non-ill will, his mind is bent by that thinking imbued with ill will. If a monk keeps pursuing thinking imbued with harmfulness, abandoning thinking imbued with harmlessness, his mind is bent by that thinking imbued with harmfulness." Sources: http://www.accesstoinsight.org/tipitaka/mn/mn.019.than.html
Misattributed

Le monde est fait pour aboutir à un beau livre.
Remark made to Jules Huret, who published it in his Enquête sur l’évolution littéraire (1891); as translated in Stéphane Mallarmé (1969) by Frederic Chase St. Aubyn, p. 23.
Observations

Source: Windsor Forest (1713), Line 13.

On Nature, as quoted by Friedrich Ueberweg, History of Philosophy, from Thales to the Present Time (1885) Vol. 1, p. 35. https://books.google.com/books?id=BW5YAAAAMAAJ&pg=PA35

Source: Birds Without Wings

Source: A Big Little Life: A Memoir of a Joyful Dog