No man can see his own prejudices.

The best road to correct reasoning is by physical science; the way to trace effects to causes is through physical science; the only corrective, therefore, of superstition is physical science.

I am neither Jew nor Gentile, Mohammedan nor Theist; I am but a member of the human family, and would accept of truth by whomsoever offered -- that truth which we can all find, if we will but seek in things, not in words; in nature, not in human imagination; in our own hearts, not in temples made with hands.

He who lives in the single exercise of his mental faculties, however usefully or curiously directed, is equally an imperfect animal with the man who knows only the exercise of muscles.

... so far from entrenching human conduct within the gentle barriers of peace and love, religion has ever been, and now is, the deepest source of contentions, wars, persecutions for conscience sake, angry words, angry feelings, backbitings, slanders, suspicions, false judgments, evil interpretations, unwise, unjust, injurious, inconsistent actions.

... your spiritual teachers caution you against enquiry--tell you not to read certain books; not to listen to certain people; to beware of profane learning; to submit your reason, and to receive their doctrines for truths. Such advice renders them suspicious counsellors.

Instead of establishing facts, we have to overthrow errors; instead of ascertaining what is, we have to chase from our imaginations what is not.