Full Idea
Cantor's development of set theory began with his discovery of the progression 0, 1, ....∞, ∞+1, ∞+2, ..∞x2, ∞x3, ...∞^2, ..∞^3, ...∞^∞, ...∞^∞^∞.....
Gist of Idea
Cantor developed sets from a progression into infinity by addition, multiplication and exponentiation
Source
report of George Cantor (Grundlagen (Foundations of Theory of Manifolds) [1883]) by Shaughan Lavine - Understanding the Infinite VIII.2
Book Reference
Lavine,Shaughan: 'Understanding the Infinite' [Harvard 1994], p.247