…among old mathematicians, I was most influenced by Euler and mostly because Euler did something that no other great mathematician of his stature did. He explained how he found his results and I was deeply interested in that. It has to do with my interest in problem solving.
[Source: George Polya Interviewed on His Ninetieth Birthday, by G. L. Alexanderson, The Two-Year College Mathematics Journal, Vol. 10, No. 1 (Jan., 1979), pp. 13-19]
Contrast this with Gauss, for example, who wrote very little, as illustrated by this famous quote:
You know that I write slowly. This is chieﬂy because I am never satisﬁed until I have said as much as possible in a few words, and writing brieﬂy takes far more time than writing at length.
Yet another reason to love Euler.