“There is always need of persons not only to discover new truths, and point out when what were once truths are true no longer, but also to commence new practices, and set the example of more enlightened conduct, and better taste and sense in human life.”

“It is given to no human being to stereotype a set of truths, and walk safely by their guidance with his mind's eye closed.”

“The real advantage which truth has, consists in this, that when an opinion is true, it may be extinguished once, twice or many times, but in the course of ages there will generally found person to rediscover it, until some of its reappearances falls on a time when from favourable circumstances it escapes persecution until it has made such head as to withstand all subsequent attempts to suppress it.”

“The idea that truth always triumphs over persecution is one of those pleasant falsehoods, which most experience refutes. History is teeming with instances of truth put down by persecution. If not put down forever, it may be set back for centuries.”

“Truth gains more even by the errors of one who, with due study and preparation, thinks for himself, than by the true opinions of those who only hold them because they do not suffer themselves to think…”

“To see the futurity of the species has always been the privilege of the intellectual elite, or of those who have learnt from them; to have the feelings of that futurity has been the distinction, and usually the martyrdom, of a still rare elite. Institutions, books, education, society, all go on training human beings for the old, long after the new has come; much more when it is only coming.”

“The peculiarity of the evidence of mathematical truths is, that all the argument is on one side. There are no objections, and no answers to objections. But on every subject on which difference of opinion is possible, the truth depends on a balance to be struck between two sets of confliting reasons. Even in natural philosophy, there is always some other explanation possible of the same facts; some geocentric theory instead of heliocentric, some phlogiston instead of oxygen; and it has to be shown why that other theory cannot be the true on: and until this is shown, and until we know how it is shown, we do not understand the grounds of our opinion. But when we turn to subjects infinitely more complicated, to morals, religion, politics, social relations, and the business of life, three-fourths of the arguments for every disputed opinion consist in dispelling the appearances which favour some opinion different from it.”