“We know very little, and yet it is astonishing that we know so much, and still more astonishing that so little knowledge can give us so much power.”

Knowledge is Power
The Note-Books of Samuel Butler (1912), Part VII - On the Making of Music, Pictures, and Books

Source: Way Station (1963), Ch. 11
Context: There was so much knowledge in the galaxy and he knew so little of it, understood so little of the little that he knew.
There were men on Earth who could make sense of it. Men who would give anything short of their very lives to know the little that he knew, and could put it all to use.
Out among the stars lay a massive body of knowledge, some of it an extension of what mankind knew, some of it concerning matters which Man had not yet suspected, and used in ways and for purposes that Man had not as yet imagined. And never might imagine, if left on his own.

volume I, "Introduction", page 3 http://darwin-online.org.uk/content/frameset?pageseq=16&itemID=F937.1&viewtype=image
Source: The Descent of Man (1871)
Context: It has often and confidently been asserted, that man's origin can never be known: but ignorance more frequently begets confidence than does knowledge: it is those who know little, and not those who know much, who so positively assert that this or that problem will never be solved by science.

Letter to Nathaniel Hawthorne, including bits of a review of his work that he had written (c. 16 April 1851); published in Nathaniel Hawthorne and His WIfe Vol, I (1884) by Julian Hawthorne, Ch. VIII : Lenox, p. 388
Context: There is a certain tragic phase of humanity which, in our opinion, was never more powerfully embodied than by Hawthorne. We mean the tragedies of human thought in its own unbiassed, native, and profounder workings. We think that into no recorded mind has the intense feeling of the usable truth ever entered more deeply than into this man's. By usable truth, we mean the apprehension of the absolute condition of present things as they strike the eye of the man who fears them not, though they do their worst to him, — the man who, like Russia or the British Empire, declares himself a sovereign nature (in himself) amid the powers of heaven, hell, and earth. He may perish; but so long as he exists he insists upon treating with all Powers upon an equal basis. If any of those other Powers choose to withhold certain secrets, let them; that does not impair my sovereignty in myself; that does not make me tributary. And perhaps, after all, there is no secret. We incline to think that the Problem of the Universe is like the Freemason's mighty secret, so terrible to all children. It turns out, at last, to consist in a triangle, a mallet, and an apron, — nothing more! We incline to think that God cannot explain His own secrets, and that He would like a little information upon certain points Himself. We mortals astonish Him as much as He us. But it is this Being of the matter; there lies the knot with which we choke ourselves. As soon as you say Me, a God, a Nature, so soon you jump off from your stool and hang from the beam. Yes, that word is the hangman. Take God out of the dictionary, and you would have Him in the street.
There is the grand truth about Nathaniel Hawthorne. He says NO! in thunder; but the Devil himself cannot make him say yes. For all men who say yes, lie; and all men who say no,—why, they are in the happy condition of judicious, unincumbered travellers in Europe; they cross the frontiers into Eternity with nothing but a carpet-bag, — that is to say, the Ego. Whereas those yes-gentry, they travel with heaps of baggage, and, damn them! they will never get through the Custom House. What's the reason, Mr. Hawthorne, that in the last stages of metaphysics a fellow always falls to swearing so? I could rip an hour.

Source: Défense des Lettres [In Defense of Letters] (1937), p. xii

For the vulpine sharpness, which considers itself to be knowledge, and "detects" in that fashion, is far mistaken. Dupes indeed are many: but, of all dupes, there is none so fatally situated as he who lives in undue terror of being duped.
1840s, Heroes and Hero-Worship (1840), The Hero As King

Letter from Johnson to John Taylor, 18 August 1763. The Yale Book of Quotations edited by Fred R. Shapiro, pg 400.