Full Idea
My proposal is that the concept of the infinite began with an extrapolation from the experience of indefinitely large size.
Gist of Idea
The infinite is extrapolation from the experience of indefinitely large size
Source
Shaughan Lavine (Understanding the Infinite [1994], VIII.2)
Book Reference
Lavine,Shaughan: 'Understanding the Infinite' [Harvard 1994], p.248
A Reaction
I think it might be better to talk of an 'abstraction' than an 'extrapolition', since the latter is just more of the same, which doesn't get you to concept. Lavine spends 100 pages working out his proposal.