Posted: Sep 18, 2015 5:03 am
by VazScep
The enumerability of the rationals is easy to discover. The hard part is coming up with the idea of one-one correspondences and then convincing others that they are a really big deal. Until then, you might not have any means to even phrase the problem, let alone get others to care about its answer.

That was the much harder task for Cantor and Dedekind, since it amounts to inventing a new field of mathematics, for which they get plenty of credit.