Full Idea
Cantor's Theorem says that for any set x, its power set P(x) has more members than x.
Gist of Idea
Cantor's Theorem: for any set x, its power set P(x) has more members than x
Source
report of George Cantor (works [1880]) by William D. Hart - The Evolution of Logic 1
Book Reference
Hart,W.D.: 'The Evolution of Logic' [CUP 2010], p.16