I don't think it's that much of a miracle - Cobham's "The intrinsic computational difficulty of functions" covered it pretty well - or least explained the intui

I don't think it's that much of a miracle - Cobham's "The intrinsic computational difficulty of functions" covered it pretty well - or least explained the intuition behind why it's a pretty sensible idea - and he (along with Jack Edmonds) pretty much defined the complexity class P.