
“When a man has put a limit on what he will do, he has put a limit on what he can do.”
Reagan reportedly displayed a plaque with this proverbial aphorism on his Oval Office desk (Michael Reagan, The New Reagan Revolution (2010), p. 177). Harry S. Truman is reported to have repeated versions of the aphorism on several occasions. This exact wording was in wide circulation in the 1960s, and the earliest known variant has been attributed to Benjamin Jowett (1817–1893).
Misattributed
“When a man has put a limit on what he will do, he has put a limit on what he can do.”
“It is amazing what you can accomplish if you do not care who gets the credit”
This is attributed to Truman in some sources, but a similar saying is recorded as early as 1909 https://books.google.com/books?id=bidJAAAAIAAJ&dq=how%20much%20%22care%20who%20gets%20the%20credit%22&pg=PA26#v=onepage&q=how%20much%20%22care%20who%20gets%20the%20credit%22&f=false.
Misattributed
Source: The Anarchist Cookbook (1971), Chapter Two: "Electronics, Sabotage, and Surveillance", p. 62.
Quoted in Bob Woodward's, State of Denial: Bush at War, Part III, Simon & Schuster, 2006
2000s, 2006
“I imagine that a hero is a man who does what he can. The others do not do it.”
Gottfried to Jean-Christophe. Part 3: Ada
Variant translation: A hero is one who does what he can. The others don't.
As quoted in A Book of French Quotations (1963) by Norbert Guterman, p. 365
Jean-Christophe (1904 - 1912), Youth (1904)
Context: You are a vain fellow. You want to be a hero. That is why you do such silly things. A hero!... I don't quite know what that is: but, you see, I imagine that a hero is a man who does what he can. The others do not do it.
“Man can do what he wills but he cannot will what he wills.”
Der Mensch kann tun was er will; er kann aber nicht wollen was er will.
Einstein paraphrasing Schopenhauer. Reportedly from On The Freedom Of The Will (1839), as translated in The Philosophy of American History: The Historical Field Theory (1945) by Morris Zucker, p. 531
Variant translations:
Man can do what he wants but he cannot want what he wants.
As quoted in The Motivated Brain: A Neurophysiological Analysis of Human Behavior (1991) by Pavel Vasilʹevich Simonov, p. 198
We can do what we wish, but we can only wish what we must.
As quoted by Einstein in "What Life Means to Einstein: An Interview by George Sylvester Viereck" The Saturday Evening Post (26 October 1929) p. 17. A scan of the article is available online here http://www.saturdayeveningpost.com/wp-content/uploads/satevepost/what_life_means_to_einstein.pdf (see p. 114).
Attributed
Source: Essays and Aphorisms