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.

Persecution for opinion is the master vice of society.

To give liberty to a slave before he understands its value is, perhaps, rather to impose a penalty than to bestow a blessing.

The man possessed of a dollar, feels himself to be not merely one hundred cents richer, but also one hundred cents better, than the man who is penniless; so on through all the gradations of earthly possessions - the estimate of our own moral and political importance swelling always in a ratio exactly proportionate to the growth of our purse.

So long as the mental and moral instruction of man is left solely in the hands of hired servants of the public--let them be teachers of religion, professors of colleges, authors of books, or editors of journals or periodical publications, dependent upon their literary incomes for their daily bread, so long shall we hear but half the truth; and well if we hear so much. Our teachers, political, scientific, moral, or religious; our writers, grave or gay, are compelled to administer to our prejudices and to perpetuate our ignorance.

... 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.

... we have broken down the self-respecting spirit of man with nursery tales and priestly threats, and we dare to assert, that inproportion as we have prostrated our understanding and degraded our nature, we have exhibited virtue, wisdom, and happiness, in our words, our actions, and our lives!