“Though one discovery always surpasses another, and though the chemical and physical knowledge accumulated since his time has gone beyond all Lavoisier's dreams, his work, like that of Newton and a few other rare spirits, will remain ever young. Certain details will age, as do the fashions of another time, but the foundation, the method, constitute one of those great aspects of the human mind, the majesty of which is only increased by years.”

January 1854
Notebooks, The English Notebooks (1853 - 1858)

Source: Gormenghast (1950), Chapter 11 (p. 440)

Introduction
Higher Mathematics for Chemical Students (1911)

The Influence of the Reformation on the Scottish Character (1865)
Context: It remains a lesson to all time, that goodness, though the indispensable adjunct to knowledge, is no substitute for it; that when conscience undertakes to dictate beyond its province, the result is only the more monstrous.
It is well that we should look this matter in the face; and as particular stories leave more impression than general statements, I will mention one, perfectly well authenticated, which I take from the official report of the proceedings:—Towards the end of 1593 there was trouble in the family of the Earl of Orkney. His brother laid a plot to murder him, and was said to have sought the help of a 'notorious witch' called Alison Balfour http://www.orkneyjar.com/folklore/witchcraft/balfour.htm. When Alison Balfour's life was looked into, no evidence could be found connecting her either with the particular offence or with witchcraft in general; but it was enough in these matters to be accused. She swore she was innocent; but her guilt was only held to be aggravated by perjury. She was tortured again and again. Her legs were put in the caschilaws — an iron frame which was gradually heated till it burned into the flesh — but no confession could be wrung from her. The caschilaws failed utterly, and something else had to be tried. She had a husband, a son, and a daughter, a child seven years old. As her own sufferings did not work upon her, she might be touched, perhaps, by the sufferings of those who were dear to her. They were brought into court, and placed at her side; and the husband first was placed in the 'lang irons' — some accursed instrument; I know not what. Still the devil did not yield. She bore this; and her son was next operated on. The boy's legs were set in 'the boot,' — the iron boot you may have heard of. The wedges were driven in, which, when forced home, crushed the very bone and marrow. Fifty-seven mallet strokes were delivered upon the wedges. Yet this, too, failed. There was no confession yet. So, last of all, the little daughter was taken. There was a machine called the piniwinkies — a kind of thumbscrew, which brought blood from under the finger nails, with a pain successfully terrible. These things were applied to the poor child's hands, and the mother's constancy broke down, and she said she would admit anything they wished. She confessed her witchcraft — so tried, she would have confessed to the seven deadly sins — and then she was burned, recalling her confession, and with her last breath protesting her innocence.
It is due to the intelligence of the time to admit that after this her guilt was doubted, and such vicarious means of extorting confession do not seem to have been tried again. Yet the men who inflicted these tortures would have borne them all themselves sooner than have done any act which they consciously knew to be wrong. They did not know that the instincts of humanity were more sacred than the logic of theology, and in fighting against the devil they were themselves doing the devil's work. We should not attempt to apologise for these things, still less to forget them. No martyrs ever suffered to instil into mankind a more wholesome lesson — more wholesome, or one more hard to learn. The more conscientious men are, the more difficult it is for them to understand that in their most cherished convictions, when they pass beyond the limits where the wise and good of all sorts agree, they may be the victims of mere delusion. Yet, after all, and happily, such cases were but few, and affected but lightly the general condition of the people.

What I Believe (1938)
Context: The people I respect most behave as if they were immortal and as if society was eternal. Both assumptions are false: both of them must be accepted as true if we are to go on eating and working and loving, and are to keep open a few breathing-holes for the human spirit. No millennium seems likely to descend upon humanity; no better and stronger Ieague of Nations will be instituted; no form of Christianity and no alternative to Christianity will bring peace to the world or integrity to the individual; no "change of heart" will occur. And yet we need not despair, indeed, we cannot despair; the evidence of history shows us that men have always insisted on behaving creatively under the shadow of the sword; that they have done their artistic and scientific and domestic stuff for the sake of doing it, and that we had better follow their example under the shadow of the aeroplanes. Others, with more vision or courage than myself, see the salvation of humanity ahead, and will dismiss my conception of civilization as paltry, a sort of tip-and-run game. Certainly it is presumptuous to say that we cannot improve, and that Man, who has only been in power for a few thousand years, will never learn to make use of his power. All I mean is that, if people continue to kill one another as they do, the world cannot get better than it is, and that, since there are more people than formerly, and their means for destroying one another superior, the world may well get worse. What is good in people — and consequently in the world — is their insistence on creation, their belief in friendship and loyalty for their own sakes; and, though Violence remains and is, indeed, the major partner in this muddled establishment, I believe that creativeness remains too, and will always assume direction when violence sleeps. So, though I am not an optimist, I cannot agree with Sophocles that it were better never to have been born. And although, like Horace, I see no evidence that each batch of births is superior to the last, I leave the field open for the more complacent view. This is such a difficult moment to live in, one cannot help getting gloomy and also a bit rattled, and perhaps short-sighted.

"Simon Stimson"
Our Town (1938)
Context: That's what it was to be alive. To move about in a cloud of ignorance; to go up and down trampling on the feelings of those... of those about you. To spend and waste time as though you had a million years. To be always at the mercy of one self-centered passion, or another. Now you know — that's the happy existence you wanted to go back to. Ignorance and blindness.

Source: 1960s - 1980s, MANAGEMENT: Tasks, Responsibilities, Practices (1973), Part 1, p. 181

John Theodore Merz, A History of European Thought in the Nineteenth Century Vol.1 http://books.google.com/books?id=xqwQAAAAYAAJ (1903)

Source: Quotes of Paul Cezanne, after 1900, Cézanne, - a Memoir with Conversations, (1897 - 1906), p. 198 in: 'What he told me – II. The Louvre'