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.

It is historically true that a large proportion of infidels in all ages have been persons of distinguished integrity and honor.

A [psychological] difficulty is not an impossibility.

Hardly any original thoughts on mental or social subjects ever make their way among mankind or assume their proper importance in the minds even of their inventors, until aptly selected words or phrases have as it were nailed them down and held them fast.

The idea is essentially repulsive, of a society held together only by the relations and feelings arising out of pecuniary interest.

A cultivated mind is one to which the fountains of knowledge have been opened, and which has been taught, in any tolerable degree, to exercise its faculties.

He must be able to hear them [the counter arguments] from persons who actually believe them; who defend them in earnest, and do their very utmost for them. He must know them in their most plausible and persuasive form; he must feel the whole force of the difficulty which the true view of the subject has to encounter and dispose of; else he will never really possess himself of the portion of truth which meets and removes that difficulty.