“There is little to be learned from those historians of morality (especially Englishmen): The usual error in their premises is their insistence on a certain consensus among human beings, at least among civilised human beings, with regard to certain propositions of morality, from thence they conclude that these propositions are absolutely binding even upon you and me; or reversely, they come to the conclusion that no morality is binding, after the truth has dawned upon them that among different peoples moral valuations are necessarily different: both of which conclusions are equally childish follies.
The error of the more subtle amongst them is that they discover and criticise the probably foolish opinions of a people about its own morality, or the opinions of mankind about human morality generally (they treat accordingly of its origin, its religious sanctions, the superstition of free will, and such matters), and they think that just by so doing they have criticised the morality itself. But the worth of a precept, "Thou shalt," is fundamentally different from and independent of such opinions about it, and must be distinguished from the weeds of error with which it has perhaps been overgrown: just as the worth of a medicine to a sick person is altogether independent of the question whether he has a scientific opinion about medicine, or merely thinks about it as an old wife would do.”