Full Idea
The Axiom of Replacement (of Skolem and Fraenkel) was remarkable for its universal acceptance, though it seemed to have no consequences except for the properties of the higher reaches of the Cantorian infinite.
Gist of Idea
Replacement was immediately accepted, despite having very few implications
Source
Shaughan Lavine (Understanding the Infinite [1994], I)
Book Reference
Lavine,Shaughan: 'Understanding the Infinite' [Harvard 1994], p.5
Related Ideas
Idea 15933 Limitation of Size: if it's the same size as a set, it's a set; it uses Replacement [Lavine]
Idea 15945 Second-order set theory just adds a version of Replacement that quantifies over functions [Lavine]