Full Idea
When two men taste the same thing one will often find it sweet and the other bitter. Suppose all men were sick, except one or two who were healthy. It would then be the latter two who would be considered sick, and the others not!
Gist of Idea
If the majority had diseased taste, and only a few were healthy, relativists would have to prefer the former
Source
Aristotle (Metaphysics [c.324 BCE], 1009b05)
Book Reference
Aristotle: 'Metaphysics', ed/tr. Lawson-Tancred,Hugh [Penguin 1998], p.99