No slave is a slave to the same lengths, and in so full a sense of the word, as a wife is.

The demand for commodities is not the demand for labor.

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.

The perpetual obstacle to human advancement is custom.

A [psychological] difficulty is not an impossibility.

There is always need of persons not only to discover new truths, and point out when what were once truths are true no longer, but also to commence new practices, and set the example of more enlightened conduct, and better taste and sense in human life.

The duty of man is the same in respect to his own nature as in respect to the nature of all other things, namely not to follow it but to amend it.