“The duty of holding a neutral conduct may be inferred, without any thing more, from the obligation which justice and humanity impose on every nation, in cases in which it is free to act, to maintain inviolate the relations of peace and amity towards other nations.”

in Indonesia, Palestine, and Kashmir - has demonstrated convincingly that parties to the most severe conflict may be induced to abandon war as the method of settlement in favour of mediation and conciliation, at a merciful saving of untold lives and acute suffering. Unfortunately, there may yet be some in the world who have not learned that today war can settle nothing, that aggressive force can never be enough, nor will it be tolerated. If this should be so, the pitiless wrath of the organized world must fall upon those who would endanger the peace for selfish ends. For in this advanced day, there is no excuse, no justification, for nations resorting to force except to repel armed attack.
Some Reflections on Peace in Our Time (1950)

2000s, 2004, Speech to United Nations General Assembly (September 2004)

1930s, Quarantine Speech (1937)

1900s, Inaugural Address (1905)

1800s, Inaugural address (1809)
Context: p>I repair to the post assigned me with no other discouragement than what springs from my own inadequacy to its high duties. If I do not sink under the weight of this deep conviction it is because I find some support in a consciousness of the purposes and a confidence in the principles which I bring with me into this arduous service...To cherish peace and friendly intercourse with all nations having correspondent dispositions; to maintain sincere neutrality toward belligerent nations; to prefer in all cases amicable discussion and reasonable accommodation of differences to a decision of them by an appeal to arms; to exclude foreign intrigues and foreign partialities, so degrading to all countries and so baneful to free ones; to foster a spirit of independence too just to invade the rights of others, too proud to surrender our own, too liberal to indulge unworthy prejudices ourselves and too elevated not to look down upon them in others; to hold the union of the States as the basis of their peace and happiness; to support the Constitution, which is the cement of the Union, as well in its limitations as in its authorities; to respect the rights and authorities reserved to the States and to the people as equally incorporated with and essential to the success of the general system; to avoid the slightest interference with the right of conscience or the functions of religion, so wisely exempted from civil jurisdiction; to preserve in their full energy the other salutary provisions in behalf of private and personal rights, and of the freedom of the press; to observe economy in public expenditures; to liberate the public resources by an honorable discharge of the public debts; to keep within the requisite limits a standing military force, always remembering that an armed and trained militia is the firmest bulwark of republics — that without standing armies their liberty can never be in danger, nor with large ones safe; to promote by authorized means improvements friendly to agriculture, to manufactures, and to external as well as internal commerce; to favor in like manner the advancement of science and the diffusion of information as the best aliment to true liberty; to carry on the benevolent plans which have been so meritoriously applied to the conversion of our aboriginal neighbors from the degradation and wretchedness of savage life to a participation of the improvements of which the human mind and manners are susceptible in a civilized state — as far as sentiments and intentions such as these can aid the fulfillment of my duty, they will be a resource which can not fail me.</p

Midwest Airlines Center, Milwaukee, Wisconsin, October 3, 2003 http://georgewbush-whitehouse.archives.gov/news/releases/2003/10/20031003-4.html
2000s, 2003

1790s, Farewell Address (1796)
Context: Observe good faith and justice towards all Nations; cultivate peace and harmony with all. Religion and Morality enjoin this conduct; and can it be, that good policy does not equally enjoin it? It will be worthy of a free, enlightened, and, at no distant period, a great Nation, to give to mankind the magnanimous and too novel example of a people always guided by an exalted justice and benevolence. Who can doubt, that, in the course of time and things, the fruits of such a plan would richly repay any temporary advantages, which might be lost by a steady adherence to it? Can it be, that Providence has not connected the permanent felicity of a Nation with its Virtue?

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.

Speech to a joint session of the Dail and the Seanad, Dublin, Ireland (28 June 1963)
1963