Full Idea
Even among practices on which all known cultures are agreed, disagreement about them may possibly exist amongst some of the nations which are unknown to us.
Gist of Idea
Even if all known nations agree on a practice, there may be unknown nations which disagree
Source
Sextus Empiricus (Outlines of Pyrrhonism [c.180], III.234)
Book Reference
Sextus Empiricus: 'Outlines of Pyrrhonism', ed/tr. Bury,R.G. [Prometheus 1990], p.267