“Since it is difficult to approve the reasons people invoke, each time we leave one of our 'fellow men', the question which comes to mind is invariably the same: how does he keep from killing himself?”

1830s, The American Scholar http://www.emersoncentral.com/amscholar.htm (1837)
Context: We will walk on our own feet; we will work with our own hands; we will speak our own minds... A nation of men will for the first time exist, because each believes himself inspired by the Divine Soul which also inspires all men.

Source: The Science of Rights 1796, P. 474, 477

Quote reported in Josiah Hotchkiss Gilbert, Dictionary of Burning Words of Brilliant Writers (1895), p. 364.
Dictionary of Burning Words of Brilliant Writers (1895)

Source: Civilization and Its Discontents

Part 3, Section 16
A Treatise of Human Nature (1739-40), Book 1: Of the understanding

Les liens entre un être et nous n'existent que dans notre pensée. La mémoire en s'affaiblissant les relâche, et, malgré l'illusion dont nous voudrions être dupes et dont, par amour, par amitié, par politesse, par respect humain, par devoir, nous dupons les autres, nous existons seuls. L'homme est l'être qui ne peut sortir de soi, qui ne connaît les autres qu'en soi, et, en disant le contraire, ment.
Source: In Search of Lost Time, Remembrance of Things Past (1913-1927), Vol. VI: The Sweet Cheat Gone (1925), Ch. I: "Grief and Oblivion"

Letter to Elias Shipman and others of New Haven (12 July 1801). Paraphrased in John B. McMaster, History of the People of the United States (ii. 586): "One sentence will undoubtedly be remembered till our republic ceases to exist. 'No duty the Executive had to perform was so trying,' [Jefferson] observed, 'as to put the right man in the right place.'"
1800s, First Presidential Administration (1801–1805)

American Diplomacy (1951), World War I
Context: There are certain sad appreciations we have to come to about human nature on the basis of these recent wars. One of them is that suffering does not always make men better. Another is that people are not always more reasonable than governments; that public opinion, or what passes for public opinion, is not invariably a moderating force in the jungle of politics. It may be true, and I suspect it is, that the mass of people everywhere are normally peace-loving and would accept many restraints and sacrifices in preference to the monstrous calamities of war. But I also suspect that what purports to be public opinion in most countries that consider themselves to have popular government is often not really the consensus of the feelings of the mass of the people at all, but rather the expression of the interests of special highly vocal minorities — politicians, commentators, and publicity-seekers of all sorts: people who live by their ability to draw attention to themselves and die, like fish out of water, if they are compelled to remain silent. These people take refuge in the pat and chauvinistic slogans because they are incapable of understanding any others, because these slogans are safer from the standpoint of short-term gain, because the truth is sometimes a poor competitor in the market place of ideas — complicated, unsatisfying, full of dilemma, always vulnerable to misinterpretation and abuse. The counsels of impatience and hatred can always be supported by the crudest and cheapest symbols; for the counsels of moderation, the reasons are often intricate, rather than emotional, and difficult to explain. And so the chauvinists of all times and places go their appointed way: plucking the easy fruits, reaping the little triumphs of the day at the expense of someone else tomorrow, deluging in noise and filth anyone who gets in their way, dancing their reckless dance on the prospects for human progress, drawing the shadow of a great doubt over the validity of democratic institutions. And until people learn to spot the fanning of mass emotions and the sowing of bitterness, suspicion, and intolerance as crimes in themselves — as perhaps the greatest disservice that can be done to the cause of popular government — this sort of thing will continue to occur.