“Translation:
That fount of mercy, whence we all exist,
Every beauty seen here [on earth] resembles,
More than anything else to knowing persons;”
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.
Original
A quel pietoso fonte, onde siam tutti, S'assembra ogni beltà che qua si vede, Più c'altra cosa alle persone accorte;
Help us to complete the source, original and additional information
Michelangelo Buonarroti 27
Italian sculptor, painter, architect and poet 1475–1564Related quotes
The Vegetarian Way, Proceedings of the 24th World Vegetarian Conference (Madras, India, 1977), p. 34; as quoted in Richard H. Schwartz, Judaism and Vegetarianism (New York: Lantern Books, 2001), p. 75 https://archive.org/stream/JudaismAndVegetarianism#page/n99/mode/2up.

“What is more important in a library than anything else — is the fact that it exists.”
"The Premise Of Meaning" in American Scholar (5 June 1972)

“Miscellaneous Observations,” Philosophical Writings, M. Stolijar, trans. (Albany: 1997) #48

“In God's eyes all children are beautiful but here on earth we have higher standards.”

Three Greek Plays, introduction (1937)
Context: There are few efforts more conducive to humility than that of the translator trying to communicate an incommunicable beauty. Yet, unless we do try, something unique and never surpassed will cease to exist, except in the libraries of a few inquisitive book lovers.

This quotation is often found on the internet attributed to Magellan, but never with a source, and no English occurrence prior to its use by Robert Green Ingersoll in his essay "Individuality" http://www.infidels.org/library/historical/robert_ingersoll/individuality.html (1873) has been located. Thus, it it most likely spurious. In that essay Ingersoll states:
It is a blessed thing that in every age some one has had individuality enough and courage enough to stand by his own convictions, — some one who had the grandeur to say his say. I believe it was Magellan who said, "The church says the earth is flat; but I have seen its shadow on the moon, and I have more confidence even in a shadow than in the church." On the prow of his ship were disobedience, defiance, scorn, and success.
Disputed
Variant: The Church says that the Earth is Flat, but I know that it is Round. For I have seen its Shadow on the Moon and I have more Faith in a Shadow than in the Church.
Source: As quoted in Oxford Academic (25 July 2013) http://oupacademic.tumblr.com/post/56463634957/misquotation-i-have-seen-the-shadow-of-the-earth