“Some things have to be seen in the shadows”

Source: The Second Summer of the Sisterhood

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

Music and Moonlight (1874), Barcarolle

To Leon Goldensohn, July 20, 1946, from "The Nuremberg Interviews" by Leon Goldensohn, Robert Gellately - History - 2004 - Page 37

Source: Summerland

"Alphabet" [Alfabet] from "Five Children's Songs" (1934), trans. John Willett in Poems, 1913-1956, p. 239
Poems, 1913-1956 (1976)

Source: Salomé

Source: The Serpent's Shadow

As quoted in Wall Street Journal (19 November 1965)
Context: I have designed my style pantomimes as white ink drawings on black backgrounds, so that man’s destiny appears as a thread lost in an endless labyrinth... I have tried to shed some gleams of light on the shadow of man startled by his anguish.