Full Idea
The stunning discovery that infinity comes in different degrees led to the theory of infinite cardinal numbers, the heart of contemporary set theory.
Gist of Idea
Infinity has degrees, and large cardinals are the heart of set theory
Source
Penelope Maddy (Naturalism in Mathematics [1997], I.1)
Book Reference
Maddy,Penelope: 'Naturalism in Mathematics' [OUP 2000], p.16
A Reaction
It occurs to me that these huge cardinals only exist in set theory. If you took away that prop, they would vanish in a puff.