“A shadow on a wall or a stray dog sleeping in the same corner can say more than statistics.”

title of his oil-painting, Dali painted in 1950
Quotes of Salvador Dali, 1941 - 1950

Source: The Way of All Flesh (1903), Ch. 72

Source: The Moving Finger

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

Variant: Because this is the other thing about immigrants: they cannot escape their history any more than you yourself can lose your shadow.
Source: White Teeth (2000)

"Evening Falls"
Song lyrics, Watermark (1988)

Swamp Thing (1983–1987)

Source: James O'Donnell Bennett (1908) When Good Fellows Get Together, p. 109