Full Idea
The idea of the 'power set' means that it is always possible to generate a bigger one using only the elements of that set, namely the set of all its subsets.
Gist of Idea
Any set can always generate a larger set - its powerset, of subsets
Source
Brian Clegg (Infinity: Quest to Think the Unthinkable [2003], Ch.14)
Book Reference
Clegg,Brian: 'Infinity' [Robinson 2003], p.184