Help us to complete the source, original and additional information
Leonardo Da Vinci 363
Italian Renaissance polymath 1452–1519Related quotes

“There is no limit to what a man can do or where he can go if he doesn't mind who gets the credit.”
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

“For he who patience hath can all things do.”
Che chi a pazienza fa ogni cosa.
XXIII, 64
Rifacimento of Orlando Innamorato

“There is no man living who isn't capable of doing more than he thinks he can do.”
“He who is bent on doing evil can never want occasion.”
Maxim 459
Sentences, The Moral Sayings of Publius Syrus, a Roman Slave

“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.

“You can easily judge the character of a man by how he treats those who can do nothing for him.”
Source: Leaders Eat Last: Why Some Teams Pull Together and Others Don't

Book III, Ode 29, lines 65–68.
Imitation of Horace (1685)