“For all of us who have been fortunate enough to make capital, we can’t take it with us in any case, so let’s act responsibly with it. Let’s put something back in.”

Source: Noli Me Tángere

Remarks at "Loyola College Alumni Banquet, Baltimore, Maryland (18 February 1958) http://www.jfklibrary.org/Research/Research-Aids/Ready-Reference/JFK-Quotations.aspx; Box 899, Senate Speech Files, John F. Kennedy Papers, Pre-Presidential Papers, John F. Kennedy Presidential Library
Pre-1960

Flying Saucers Have Landed

Account of his famous dream of the benzene structure, as quoted in A Life of Magic Chemistry : Autobiographical Reflections of a Nobel Prize Winner (2001) by George A. Olah, p. 54<!-- also partially quoted in Serendipity, Accidental Discoveries in Science (1989) by Royston M. Roberts , pp. 75-81 -->
Context: I was sitting writing on my textbook, but the work did not progress; my thoughts were elsewhere. I turned my chair to the fire and dozed. Again the atoms were gamboling before my eyes. This time the smaller groups kept modestly in the background. My mental eye, rendered more acute by the repeated visions of the kind, could now distinguish larger structures of manifold conformation; long rows sometimes more closely fitted together all twining and twisting in snake-like motion. But look! What was that? One of the snakes had seized hold of its own tail, and the form whirled mockingly before my eyes. As if by a flash of lightning I awoke; and this time also I spent the rest of the night in working out the consequences of the hypothesis. Let us learn to dream, gentlemen, and then perhaps we shall learn the truth... but let us beware of publishing our dreams before they have been put to the proof by the waking understanding.

Letter to James Madison, 30 November 1785 https://books.google.com/books?id=64MTAQAAMAAJ&pg=PA25
1780s

Source: The Fountainhead

The Future of Civilization (1938)
Context: Do not let us underrate the danger. It threatens everything we care for. For if it does succeed, it will not only bring us back to 1914 — in itself bad enough — but to something far worse even than that. For instance, it is now apparently part of the normal doctrine of those who advocate this system that no distinction can be made between combatants and non-combatants, and that a perfectly legitimate and indeed necessary method of warfare will be the wholesale destruction of unfortified cities and their inhabitants. No doubt there will be countervailing efforts to prevent such things happening; but there is, at any rate, one section of military thought which believes that the only way to stop the bombardment of the cities belonging to one belligerent will be the bombardment of the cities belonging to the other.

Speech https://cain.ulster.ac.uk/issues/politics/docs/dup/pr290312.htm to the Ulster Unionist Council in Belfast (4 February 1921), quoted in Geoffrey Lewis, Carson: The Man Who Divided Ireland (2006), pp. 227–28