“[T]he ancient philosophers… all of them assert that the elements, and those things which are called by them principles, are contraries, though they establish them without reason, as if they were compelled to assert this by truth itself. They differ, however… that some of them assume prior, and others posterior principles; and some of them things more known according to reason, but others such as are more known according to sense: for some establish the hot and the cold, others the moist and the dry, others the odd and the even, and others strife and friendship, as the causes of generation. …in a certain respect they assert the same things, and speak differently from each other. They assert different things… but the same things, so far as they speak analogously. For they assume principles from the same co-ordination; since, of contraries, some contain, and others are contained.”

Book I, Ch. VI, pp. 53-55.
Physics

I, q. 32, art. 1, reply obj. 2
Summa Theologica (1265–1274)

Omnipotence and Other Theological Mistakes (1984)

Book II, Ch. I, p. 88.
Physics

Book I, Ch. VII, pp. 62-63.
Physics

Independence Day speech (1828)
Context: There is, in the institutions of this country, one principle, which, had they no other excellence, would secure to them the preference over those of all other countries. I mean — and some devout patriots will start — I mean the principle of change.
I have used a word to which is attached an obnoxious meaning. Speak of change, and the world is in alarm. And yet where do we not see change? What is there in the physical world but change? And what would there be in the moral world without change?

Book II, Ch. 5, p. 345, as quoted in Atheism from the Reformation to the Enlightenment‎ (1992) edited by Michael Cyril William Hunter and David Wootton, p. 99
De la sagesse (1601)
Context: All Religions have this in common, that they are an outrage to common sense for they are pieced together out of a variety of elements, some of which seem so unworthy, sordid and at odds with man’s reason, that any strong and vigorous intelligence laughs at them; but others are so noble, illustrious, miraculous, and mysterious that the intellect can make no sense of them and finds them unpalatable. The human intellect is only capable of tackling mediocre subjects: it disdains petty subjects, and is startled by large ones. There is no reason to be surprised if it finds any religion hard to accept at first, for all are deficient in the mediocre and the commonplace, nor that it should require skill to induce belief. For the strong intellect laughs at religion, while the weak and superstitious mind marvels at it but is easily scandalized by it.

Address to the Prague World Congress of International PEN Club (7 November 1994) http://www.englishpen.org/writersinprison/wipcnews/peninternationaldeeplysaddenedbydeathofvclavhavelaconstantchampionforfreedomofexpression/

Source: A Theory of Justice (1971; 1975; 1999), Chapter III, Section 29, pg.177