“Distinguish between the outlawry of war and the abolition of war. The former is only a step in the direction of the latter.”

6 December 1748
Letters to His Son on the Art of Becoming a Man of the World and a Gentleman (1774)

"The Question of Peace" (July–August 1915) http://www.marxists.org/archive/lenin/works/1915/jul/x02.htm; Collected Works, Vol. 21, p. 293.
1910s

Source: The Perpetual Calendar of Inspiration

Source: The Revolt of the Masses (1929), Chapter XIV: Who Rules The World?
Context: Nationalism is always an effort in a direction opposite to that of the principle which creates nations. The former is exclusive in tendency, the latter inclusive. In periods of consolidation, nationalism has a positive value, and is a lofty standard. But in Europe everything is more than consolidated, and nationalism is nothing but a mania, a pretext to escape from the necessity of inventing something new, some great enterprise.

'Aids to Reflection (1873), Aphorism 26

“Commerce and Culture,” p. 281.
Giants and Dwarfs (1990)

Context: I make this chief distinction between religion and superstition, that the latter is founded on ignorance, the former on knowledge; this, I take it, is the reason why Christians are distinguished from the rest of the world, not by faith, nor by charity, nor by the other fruits of the Holy Spirit, but solely by their opinions, inasmuch as they defend their cause, like everyone else, by miracles, that is by ignorance, which is the source of all malice; thus they turn a faith, which may be true, into superstition.

Letter 21 (73) to Henry Oldenburg , November (1675)

The Pathway of Peace (1923)
Context: It is not surprising that many should be captivated by the proposal, with its delusive simplicity and adequacey, for the outlawry of war. War should be made a crime, and those who instigate it should be punished as criminals. The suggestion, however futile in itself, has at least the merit of bringing us to the core of the problem. Even among its sponsors appear at once the qualifications which reflect the old distinction, so elaborately argued by Grotius, between just and unjust wars. "The grounds of war," said he, " are as numerous as those of judicial actions. For where the power of law ceases, there war begins." He found the justifiable causes generally assigned for war to be three — defense, indemnity, and punishment. War is self-help, and the right to make war has been recognized as the corollary of independence, the permitted means by which injured nations protect their territory and maintain their rights. International law leaves aggrieved states who cannot obtain redress for their wrongs by peaceful means to exact it by force. If war is outlawed, other means of redress of injuries must be provided. Moreover, few, if any, intend to outlaw self-defense, a right still accorded to individuals under all systems of law. To meet this difficulty, the usual formula is limited to wars of aggression. But justification for war, as recently demonstrated, is ready at hand for those who desire to make war, and there is rarely a case of admitted aggression, or where on each side the cause is not believed to be just by the peoples who support the war.
There is a further difficulty that lies deeper. There is no lawgiver for independent States. There is no legislature to impose its will by majority vote, no executive to give effect even to accepted rules. The outlawry of war necessarily implies a self-imposed restraint, and free peoples, jealous of their national safety, of their freedom of opportunity, of the rights and privileges they deem essential to their well-being, will not forego the only sanction at their command in extreme exigencies. The restraints they may be willing to place upon themselves will always be subject to such conditions as will leave them able to afford self-protection by force, and in this freedom there is abundant room for strife sought to be justified by deep-seated convictions of national interests, by long-standing grievances by the apprehension of aggression to be forestalled. The outlawry of war, by appropriate rule of law making war a crime, requires the common accord needed to establish and maintain a rule of international law, the common consent to abandon war; and the suggested remedy thus implies a state of mind in which no cure is needed. As the restraint is self-imposed it will prove to be of avail only while there is a will to peace.

Hardball with Chris Matthews, November 16 2004
2000s