Fecundity

And he put it to us in this way—marking the points with a lean forefinger—as we sat and lazily admired his earnestness over this new paradox (as we thought it) and his fecundity.

Source: tatoeba (8214989)

In the early days the reviewers compared him to the late Douglas Adams, but then Terry went on to write books as enthusiastically as Douglas avoided writing them, and now, if there is any comparison to be made of anything from the formal rules of a Pratchett novel to the sheer prolific fecundity of the man, it might be to P. G. Wodehouse.

Source: wiktionary

[I]t would not be very much less absurd for someone to write about New York City after having spent only a few years or a few decades in this metropolis of inexhaustible adventure, of terrifying emotional fecundity, of uncapturable character.

Source: wiktionary

The soil spawned humanity, as it bred frogs in the Rains, and the gap of the sickness of one season was filled to overflowing by the fecundity of the next.

Source: wiktionary