“One seldom recognizes the devil when he is putting his hand on your shoulder.”
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Albert Speer 21
German architect, Minister of Armaments and War Production … 1905–1981Related quotes

Vain Fortune, Chapter 2.

“When anyone says he’s a country boy, put your hand on your wallet.”
While Lyndon Johnson is reported to have said this (or a variation), it was not original to him. See barrypopik.com http://www.barrypopik.com/index.php/new_york_city/entry/when_anyone_says_hes_a_country_boy_you_better_put_your_hand_on_your_wallet and Texas, A Modern History: Revised Edition https://books.google.com/books?id=WQNo7e3jjysC&pg=PA215#v=onepage&q&f=false.
Misattributed

“Like him in Æsop, he whipped his horses withal, and put his shoulder to the wheel.”
Section 1, member 2, Lawful Cures, first from God.
The Anatomy of Melancholy (1621), Part II

“Put your shoulder to the wheel.”
Hercules and the Wagoner.

Source: Roots : The Saga of an American Family (1976), Ch. 51.

Muhammad: A Prophet of Our Times
Muhammad: A Biography of The Prophet (2001)

“Man can hardly even recognize the devils of his own creation.”
This quote was attributed to Albert Schweitzer by Rachel Carson on p. 17 of her seminal work Silent Spring (1962), and is widely cited on various Internet websites, but an actual source from Schweitzer’s works is elusive.
Disputed