Letter to William Thomson (2 January 1851), indicating his early work on what has since become known as Boolean logic.
1850s
Context: I am now about to set seriously to work upon preparing for the press an account of my theory of Logic and Probabilities which in its present state I look upon as the most valuable if not the only valuable contribution that I have made or am likely to make to Science and the thing by which I would desire if at all to be remembered hereafter.
The Rationality of Induction, Oxford: Clarendon, 1986. Page 176, last paragraph.
Book IV, Ch. 19 : Of Enthusiasm (Chapter added in the fourth edition).
Variant paraphrase, sometimes cited as a direct quote: One unerring mark of the love of truth is not entertaining any proposition with greater assurance than the proofs it is built upon will warrant.
As paraphrased in Peter's Quotations : Ideas for our Time (1979) by Laurence J. Peter, p. 500; also in The Demon-Haunted World : Science as a Candle in the Dark (1994) by Carl Sagan, p. 64
An Essay Concerning Human Understanding (1689)
Context: He that would seriously set upon the search of truth, ought in the first place to prepare his mind with a love of it. For he that loves it not, will not take much pains to get it; nor be much concerned when he misses it. There is nobody in the commonwealth of learning who does not profess himself a lover of truth: and there is not a rational creature that would not take it amiss to be thought otherwise of. And yet, for all this, one may truly say, that there are very few lovers of truth, for truth's sake, even amongst those who persuade themselves that they are so. How a man may know whether he be so in earnest, is worth inquiry: and I think there is one unerring mark of it, viz. The not entertaining any proposition with greater assurance than the proofs it is built upon will warrant. Whoever goes beyond this measure of assent, it is plain receives not the truth in the love of it; loves not truth for truth's sake, but for some other bye-end.
Speech in Perth (4 July 1983), quoted in Paul Routledge, "Pit leaders seek backing for big pay increases", The Times (5 July 1983), p. 1
Source: Books, The End of Racism (1995), Ch. 7
The Conscious Mind: In Search of a Fundamental Theory (1996)
“I know now that there are things for which I am prepared to die.”
"Dilemma of a Pacifist"(1937)
Context: I know now that there are things for which I am prepared to die. I am willing to die for political freedom; for the right to give my loyalty to ideals above a nation and above a class; for the right to teach my child what I think to be the truth; for the right to explore such knowledge as my brains can penetrate; for the right to love where my mind and heart admire, without reference to some dictator’s code to tell me what the national canons on the matter are; for the right to work with others of like mind; for a society that seems to me becoming to the dignity of the human race.
I shall pick no fight, nor seek to impose by force these standards on others. But let it be clear. If the fight comes unsolicited, I am not willing to die meekly, to surrender without effort. And that being so, am I still a pacifist?
In 1957; p. 35
before 1960, "Yves Klein, 1928 – 1962, Selected Writings"
Quote in Chagall's letter to A. N. Benois, 1911, as cited in Marc Chagall - the Russian years 1906 – 1922, editor Christoph Vitali, exhibition catalogue, Schirn Kunsthalle Frankfurt, 1991, p. 146
1910's
