Life has a certain flavor for those who have fought and risked all that the sheltered and protected can never experience.

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.

... the besetting danger is not so much of embracing falsehood for truth, as of mistaking a part of the truth for the whole.

We have hitherto considered only two possibilities: that the received opinion may be false, and some other opinion, consequently, true; or that, the received opinion being true, a conflict with the opposite error is essential to a clear apprehension and deep feeling of its truth. But there is a commoner case than either of these; when the conflicting doctrines, instead of being one true and the other false, share the truth between them.

Truth emerges from the clash of adverse ideas.

Let not any one pacify his conscience by the delusion that he can do no harm if he takes no part, and forms no opinion. Bad men need nothing more to compass their ends, than that good men should look on and do nothing.

The feeling of a direct responsibility of the individual to God is almost wholly a creation of Protestantism.