For if it were proposed to all nations to choose which seemed best of all customs, each, after examination, would place its own first; so well is each convinced that its own are by far the best. I will give this one proof among many from which it may be inferred that all men hold this belief about their customs. It is not therefore to be supposed that anyone, except a madman, would turn such things to ridicule. I will give this one proof among many from which it may be inferred that all men hold this belief about their customs.
When Darius was king, he summoned the Greeks who were with him and asked them for what price they would eat their fathers’ dead bodies. They answered that there was no price for which they would do it.
Then Darius summoned those Indians who are called Callatiae, who eat their parents, and asked them (the Greeks being present and understanding through interpreters what was said) what would make them willing to burn their fathers at death. The Indians cried aloud, that he should not speak of so horrid an act. So firmly rooted are these beliefs; and it is, I think, rightly said in Pindar’s poem that custom is lord of all [Herodotus, The Histories 3:38:1b-4].
In context, Herodotus takes Cambyses as the exemplar madman who ridicules custom. This is one of the very few places where Herodotus appears to expose his own view on custom and religion. Another is 2:3:2,
Now, such stories as I heard about the gods I am not ready to relate, except their names, for I believe that all men are equally knowledgeable about them; and I shall say about them what I am constrained to say by the course of my history.
I don’t fully agree with Herodotus on this. Herodotus thought that “all men are equally knowledgeable” of the gods. Had he lived 23 or so centuries later he might have framed his sentence somewhat differently. All people are equally ignorant of the gods. At least that’s they way I would say it. From this, it’s not a far stretch to Mark Twain’s observation, “The easy confidence with which I know another man’s religion is folly teaches me to suspect that my own is also [apud Paine, Mark Twain: a Biography].” Ignoring what Herodotus tells us of Cambyses and considering only our ignorance of the gods, who is the madman, the believer or the skeptic?