“The pride of the intellect: The intellect is the most incredible human capacity. It is the highest of all human capacities, actually. However, it is also the thing that can go most terribly wrong, because the intellect can become arrogant about its own existence and its accomplishments, and it can fall in love with its own products. That's what happens with ideologies. You become obsessed with a human-constructed dogma of which you believe is 100% right, and it eradicates the necessity of anything transcendent.”

In the 1661 translation by Thomas Salusbury: … such are the pure Mathematical sciences, to wit, Geometry and Arithmetick: in which Divine Wisdom knows infinite more propositions, because it knows them all; but I believe that the knowledge of those few comprehended by humane understanding, equalleth the divine, as to the certainty objectivè, for that it arriveth to comprehend the neces­sity thereof, than which there can be no greater certainty." p. 92 (from the Archimedes Project http://archimedes.mpiwg-berlin.mpg.de/cgi-bin/toc/toc.cgi?page=92;dir=galil_syste_065_en_1661;step=textonly)
In the original Italian: … tali sono le scienze matematiche pure, cioè la geometria e l’aritmetica, delle quali l’intelletto divino ne sa bene infinite proposizioni di piú, perché le sa tutte, ma di quelle poche intese dall’intelletto umano credo che la cognizione agguagli la divina nella certezza obiettiva, poiché arriva a comprenderne la necessità, sopra la quale non par che possa esser sicurezza maggiore." (from the copy at the Italian Wikisource).
Dialogue Concerning the Two Chief World Systems (1632)

Source: A Connecticut Yankee in King Arthur's Court

the happening world (15) “Equal and Opposite”
Stand on Zanzibar (1968)

Other

volume II, chapter VII: "The 'Origin of Species'", pages 311-312 http://darwin-online.org.uk/content/frameset?pageseq=327&itemID=F1452.2&viewtype=image; letter http://www.darwinproject.ac.uk/entry-2814 to Asa Gray (22 May 1860)
"Ichneumonidæ" sometimes altered to "parasitic wasps" in paraphrases of this passage.
Paraphrased as "I feel most deeply that this whole question of Creation is too profound for human intellect. A dog might as well speculate on the mind of Newton! Let each man hope and believe what he can." Elbert Hubbard, Little Journeys to the Homes of Great Scientists (1916) page 197 http://books.google.com/books?id=nYArAQAAMAAJ&pg=PA198&f=false. <!-- Sometimes claimed that this appeared in Illustrated London News (21 April 1862), but a full search of every issue of Illustrated London News (1842–2003) through Gale Digital News Vault shows that this passage never appeared. -->
The Life and Letters of Charles Darwin (1887)
Context: With respect to the theological view of the question. This is always painful to me. I am bewildered. I had no intention to write atheistically. But I own that I cannot see as plainly as others do, and as I should wish to do, evidence of design and beneficence on all sides of us. There seems to me too much misery in the world. I cannot persuade myself that a beneficent and omnipotent God would have designedly created the Ichneumonidæ with the express intention of their feeding within the living bodies of Caterpillars, or that a cat should play with mice. Not believing this, I see no necessity in the belief that the eye was expressly designed. On the other hand, I cannot anyhow be contented to view this wonderful universe, and especially the nature of man, and to conclude that everything is the result of brute force. I am inclined to look at everything as resulting from designed laws, with the details, whether good or bad, left to the working out of what we may call chance. Not that this notion at all satisfies me. I feel most deeply that the whole subject is too profound for the human intellect. A dog might as well speculate on the mind of Newton. Let each man hope and believe what he can. Certainly I agree with you that my views are not at all necessarily atheistical.

Greater than Sky, Vaster than Space, (2018), Part I