“A power has risen up in the government greater than the people themselves, consisting of many and various and powerful interests, combined into one mass, and held together by the cohesive power of the vast surplus in the banks.”

The Director, in Ch 10
Brave New World (1932)

The earliest known appearance of this statement is from 1895 (Joshua Douglass, "Bimetallism and Currency", American Magazine of Civics, 7:256). It is apparently a combination of paraphrases or approximate quotations from three separate letters of Jefferson (longer excerpts in sourced section):
I sincerely believe, with you, that banking institutions are more dangerous than standing armies...
Letter to John Taylor (1816)
The bank mania...is raising up a moneyed aristocracy in our country which has already set the government at defiance...
Letter to Josephus B. Stuart (1817)
Bank paper must be suppressed, and the circulating medium must be restored to the nation to whom it belongs.
Letter to John W. Eppes (1813)
Misattributed

You Can't Be Neutral on A Moving Train (1994) Ch. 4: "My Name is Freedom": Albany, Georgia
Context: The white population could not possibly be unaffected by those events — some whites more stubborn in their defense of segregation, but others beginning to think in different ways. And the black population was transformed, having risen up in mass action for the first time, feeling its power, knowing now that if the old order could be shaken it could be toppled.

Es liegt nicht in meiner Macht – und nicht in der Macht irgendeines Menschen in Deutschland – zu bestimmen, wie viele Menschen hierher kommen.
Merkel interviewed by Anne Will (German talk show) on October 7, 2015, "Angela Merkel: There will be no stop of receiving (refugees)" https://www.tagesspiegel.de/politik/fluechtlingspolitik-angela-merkel-den-aufnahmestopp-gibt-es-nicht/12422322.html,, October 10, 2015.
2015

Source: Soldiers Live (2000), Chapter 23, “Glittering Stone: Fortress with No Name” (p. 448)

Source: Malcolm X Speaks (1965), p. 158

Source: Darkfever

Source: Ideas have Consequences (1948), p. 13.
Context: In the popular arena, one can tell … that the average man … imagines that an industrious acquisition of particulars will render him a man of knowledge. With what pathetic trust does he recite his facts! He has been told that knowledge is power, and knowledge consists of a great many small things.

ibid
Drenai series, Waylander II: In the Realm of the Wolf