“This is indeed a maxim of general application…Nations cannot be governed by the obligations of friendship which prevail among individuals in private life…There can be, in the eyes of a philosophical statesman neither national enmities, nor national friendships.”

First annual message to Congress (1 June 1841).

Addressing the House of Commons after the assassination of Abraham Lincoln (1 May 1865).
1860s
Context: There are rare instances when the sympathy of a nation approaches those tenderer feelings which are generally supposed to be peculiar to the individual, and to be the happy privilege of private life, and this is one. Under any circumstances we should have bewailed the catastrophe at Washington; under any circumstances we should have shuddered at the means by which it was accomplished. But in the character of the victim, and even in the accessories of his last moments, there is something so homely and innocent, that it takes the question, as it were, out of all the pomp of history and the ceremonial of diplomacy; it touches the heart of nations, and appeals to the domestic sentiment of mankind.
Whatever the various and varying opinions in this House, and in the country generally, on the policy of the late President of the United States, all must agree that in one of the severest trials which ever tested the moral qualities of man he fulfilled his duty with simplicity and strength. …When such crimes are perpetrated the public mind is apt to fall into gloom and perplexity, for it is ignorant alike of the causes and the consequences of such deeds. But it is one of our duties to reassure them under unreasoning panic and despondency. Assassination has never changed the history of the world. I will not refer to the remote past, though an accident has made the most memorable instance of antiquity at this moment fresh in the minds and memory of all around me. But even the costly sacrifice of a Caesar did not propitiate the inexorable destiny of his country.

Speech http://hansard.millbanksystems.com/commons/1849/feb/02/the-address-in-answer-to-the-speech#column_206 in the House of Commons (2 February 1849)
1840s

The Friendship Case: Space Brothers teach lessons of brotherhood – an excerpt by Gerard Aartsen Share International http://share-international.org/magazine/old_issues/2011/2011-04.htm#correo (2011)

1800s, First Inaugural Address (1801)
Context: Equal and exact justice to all men, of whatever state or persuasion, religious or political; peace, commerce, and honest friendship with all nations, entangling alliances with none; the support of the State governments in all their rights, as the most competent administrations for our domestic concerns and the surest bulwarks against antirepublican tendencies; the preservation of the General Government in its whole constitutional vigor, as the sheet anchor of our peace at home and safety abroad; a jealous care of the right of election by the people -- a mild and safe corrective of abuses which are lopped by the sword of revolution where peaceable remedies are unprovided; absolute acquiescence in the decisions of the majority, the vital principle of republics, from which is no appeal but to force, the vital principle and immediate parent of despotism; a well-disciplined militia, our best reliance in peace and for the first moments of war till regulars may relieve them; the supremacy of the civil over the military authority; economy in the public expense, that labor may be lightly burthened; the honest payment of our debts and sacred preservation of the public faith; encouragement of agriculture, and of commerce as its handmaid; the diffusion of information and arraignment of all abuses at the bar of the public reason; freedom of religion; freedom of the press, and freedom of person under the protection of the habeas corpus, and trial by juries impartially selected. These principles
Context: About to enter, fellow-citizens, on the exercise of duties which comprehend everything dear and valuable to you, it is proper you should understand what I deem the essential principles of our Government, and consequently those which ought to shape its Administration. I will compress them within the narrowest compass they will bear, stating the general principle, but not all its limitations. Equal and exact justice to all men, of whatever state or persuasion, religious or political; peace, commerce, and honest friendship with all nations, entangling alliances with none; the support of the State governments in all their rights, as the most competent administrations for our domestic concerns and the surest bulwarks against antirepublican tendencies; the preservation of the General Government in its whole constitutional vigor, as the sheet anchor of our peace at home and safety abroad; a jealous care of the right of election by the people -- a mild and safe corrective of abuses which are lopped by the sword of revolution where peaceable remedies are unprovided; absolute acquiescence in the decisions of the majority, the vital principle of republics, from which is no appeal but to force, the vital principle and immediate parent of despotism; a well-disciplined militia, our best reliance in peace and for the first moments of war till regulars may relieve them; the supremacy of the civil over the military authority; economy in the public expense, that labor may be lightly burthened; the honest payment of our debts and sacred preservation of the public faith; encouragement of agriculture, and of commerce as its handmaid; the diffusion of information and arraignment of all abuses at the bar of the public reason; freedom of religion; freedom of the press, and freedom of person under the protection of the habeas corpus, and trial by juries impartially selected. These principles form the bright constellation which has gone before us and guided our steps through an age of revolution and reformation. The wisdom of our sages and blood of our heroes have been devoted to their attainment. They should be the creed of our political faith, the text of civic instruction, the touchstone by which to try the services of those we trust; and should we wander from them in moments of error or of alarm, let us hasten to retrace our steps and to regain the road which alone leads to peace, liberty, and safety.

Letter to http://memory.loc.gov/cgi-bin/query/r?ammem/mtj:@field(DOCID+@lit(tj110158)) Thomas Leiper (12 June 1815). Published in The Works of Thomas Jefferson in Twelve Volumes http://oll.libertyfund.org/ToC/0054.php, Federal Edition, Paul Leicester Ford, ed., New York: G. P. Putnam's Sons, 1904, Vol. 11 http://oll.libertyfund.org/Texts/Jefferson0136/Works/0054-11_Bk.pdf, pp. 477–478.
The sentence "I hope our wisdom will grow with our power, and teach us, that the less we use our power, the greater it will be." was used by US-President Barack Obama in his A New Beginning Speech.
1810s
Context: We concur in considering the government of England as totally without morality, insolent beyond bearing, inflated with vanity and ambition, aiming at the exclusive dominion of the sea, lost in corruption, of deep-rooted hatred towards us, hostile to liberty wherever it endeavors to show its head, and the eternal disturber of the peace of the world. In our estimate of Bonaparte, I suspect we differ. [... ] Our form of government is odious to him, as a standing contrast between republican and despotic rule; and as much from that hatred, as from ignorance in political economy, he had excluded intercourse between us and his people, by prohibiting the only articles they wanted from us, that is, cotton and tobacco. Whether the war we have had with England, and the achievements of that war, and the hope that we may become his instruments and partisans against that enemy, may induce him, in future, to tolerate our commercial intercourse with his people, is still to be seen. For my part, I wish that all nations may recover and retain their independence; that those which are overgrown may not advance beyond safe measures of power, that a salutary balance may be ever maintained among nations, and that our peace, commerce, and friendship, may be sought and cultivated by all. It is our business to manufacture for ourselves whatever we can, to keep our markets open for what we can spare or want; and the less we have to do with the amities or enmities of Europe, the better. Not in our day, but at no distant one, we may shake a rod over the heads of all, which may make the stoutest of them tremble. But I hope our wisdom will grow with our power, and teach us, that the less we use our power, the greater it will be.

Source: Liberalism (1927), Ch. 1 : The Foundations of Liberal Policy § 10 : The Argument of Fascism
Context: Repression by brute force is always a confession of the inability to make use of the better weapons of the intellect — better because they alone give promise of final success. This is the fundamental error from which Fascism suffers and which will ultimately cause its downfall. The victory of Fascism in a number of countries is only an episode in the long series of struggles over the problem of property. The next episode will be the victory of Communism. The ultimate outcome of the struggle, however, will not be decided by arms, but by ideas. It is ideas that group men into fighting factions, that press the weapons into their hands, and that determine against whom and for whom the weapons shall be used. It is they alone, and not arms, that, in the last analysis, turn the scales.
So much for the domestic policy of Fascism. That its foreign policy, based as it is on the avowed principle of force in international relations, cannot fail to give rise to an endless series of wars that must destroy all of modern civilization requires no further discussion. To maintain and further raise our present level of economic development, peace among nations must be assured. But they cannot live together in peace if the basic tenet of the ideology by which they are governed is the belief that one's own nation can secure its place in the community of nations by force alone.
It cannot be denied that Fascism and similar movements aiming at the establishment of dictatorships are full of the best intentions and that their intervention has, for the moment, saved European civilization. The merit that Fascism has thereby won for itself will live on eternally in history. But though its policy has brought salvation for the moment, it is not of the kind which could promise continued success. Fascism was an emergency makeshift. To view it as something more would be a fatal error.

1910s, The New Nationalism (1910)
Context: Justice and fair dealings among nations rest upon principles identical with those which control justice and fair dealing among the individuals of which nations are composed, with the vital exception that each nation must do its own part in international police work. If you get into trouble here, you can call for the police; but if Uncle Sam gets into trouble, he has got to be his own policeman, and I want to see him strong enough to encourage the peaceful aspirations of other people’s in connection with us. I believe in national friendships and heartiest good-will to all nations; but national friendships, like those between men, must be founded on respect as well as on liking, on forbearance as well as upon trust. I should be heartily ashamed of any American who did not try to make the American government act as justly toward the other nations in international relations as he himself would act toward any individual in private relations. I should be heartily ashamed to see us wrong a weaker power, and I should hang my head forever if we tamely suffered wrong from a stronger power.

As quoted in Hitler (1974) by Joachim C. Fest, p. 533
Other remarks