“Someone will say: And are you not ashamed, Socrates, of a course of life which is likely to bring you to an untimely end? To him I may fairly answer: There you are mistaken: a man who is good for anything ought not to calculate the chance of living or dying; he ought only to consider whether in doing anything he is doing right or wrong — acting the part of a good man or a bad. …For wherever a man's place is, whether the place he has chosen or that where he has been placed by a commander. there he ought to remain in the hour of danger; he should not think of death or of anything, but of disgrace.”

The last sentence is from the 16 October 1854 Peoria speech, slightly paraphrased. No known contemporary source for the rest. It first appears, attributed to Lincoln, in US religious/inspirational journals in 1907-8, such as p123, Friends Intelligencer: a religious and family journal, Volume 65, Issue 8 (1908)
Misattributed

33a–b
Plato, Apology

XI, 15
Meditations (c. 121–180 AD), Book XI
Source: The Apology, Phaedo & Crito of Plato/Golden Sayings of Epictetus/Meditations of Marcus Aurelius

#975
The Furrow (1986)

Source: Social Problems (1883), Ch. 21 : Conclusion
Context: Many there are, too depressed, too embruted with hard toil and the struggle for animal existence, to think for themselves. Therefore the obligation devolves with all the more force on those who can. If thinking men are few, they are for that reason all the more powerful. Let no man imagine that he has no influence. Whoever he may be, and wherever he may be placed, the man who thinks becomes a light and a power. That for every idle word men may speak they shall give an account at the day of judgment, seems a hard saying. But what more clear than that the theory of the persistence of force, which teaches us that every movement continues to act and react, must apply as well to the universe of mind as to that of matter? Whoever becomes imbued with a noble idea kindles a flame from which other torches are lit, and influences those with whom he comes in contact, be they few or many. How far that influence, thus perpetuated, may extend, it is not given to him here to see. But it may be that the Lord of the Vineyard will know.

The Notebooks of Leonardo Da Vinci (1938), XXIX Precepts of the Painter

"Slaves of Silver", Galaxy, 1971, Reprinted in Gene Wolfe, Storeys from the Old Hotel (1988)
Fiction

The Dublin Nation, Sept. 28, 1844, Vol. ii. p. 809, reported in Bartlett's Familiar Quotations, 10th ed. (1919).

1910s, Address to the Knights of Columbus (1915)
Context: The one absolutely certain way of bringing this nation to ruin, of preventing all possibility of its continuing to be a nation at all, would be to permit it to become a tangle of squabbling nationalities, an intricate knot of German-Americans, Irish-Americans, English-Americans, French-Americans, Scandinavian-Americans or Italian-Americans, each preserving its separate nationality, each at heart feeling more sympathy with Europeans of that nationality, than with the other citizens of the American Republic. The men who do not become Americans and nothing else are hyphenated Americans; and there ought to be no room for them in this country. The man who calls himself an American citizen and who yet shows by his actions that he is primarily the citizen of a foreign land, plays a thoroughly mischievous part in the life of our body politic. He has no place here; and the sooner he returns to the land to which he feels his real heart allegiance, the better it will be for every good American. There is no such thing as a hyphenated American who is a good American. The only man who is a good American is the man who is an American and nothing else.