An opinion, right or wrong, can never constitute a moral offense, nor be in itself a moral obligation. It may be mistaken; it may involve an absurdity, or a contradiction. It is a truth; or it is an error: it can never be a crime or a virtue.

The simplest principles become difficult of practice, when habits, formed in error, have been fixed by time, and the simplest truths hard to receive when prejudice has warped the mind.

the mode of delivering a truth makes, for the most part, as much impression on the mind of the listener as the truth itself.

Credulity is always ridiculous.

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.

Fathers and husbands! do ye not also understand this fact? Do ye not see how, in the mental bondage of your wives and fair companions, ye yourselves are bound?

Trust me, there are as many ways of living as there are men, and one is no more fit to lead another, than a bird to lead a fish, or a fish a quadruped.