For the dummies like me, what is it that is meant with carrier and group here below?
So when we say that the carrier of a group is a set, it doesn’t have
to be specifically a ZF set; but if we imagine collecting up all
groups as a single entity, that warning light should flash. It’s
dangerous to take the collection of all sets as a single entity, then
to build on top of that. And yet, that is precisely what is done in
category theory, again and again.
