The god who is reputed to have created fleas to keep dogs from moping over their situation must also have created fundamentalists to keep rationalists from getting flabby. Let us be duly thankful for out blessings.

Hardin uses a sardonic analogy—fleas as a perverse “gift” that keeps dogs alert—to argue that intellectual opponents can serve a similar function. “Fundamentalists,” in his framing, act as an irritant that prevents “rationalists” from becoming complacent, lazy, or self-satisfied (“flabby”). The closing line (“Let us be duly thankful…”) heightens the irony: he is not praising fundamentalism’s claims, but suggesting that the presence of dogmatic adversaries can sharpen critical thinking, force clearer argumentation, and keep secular or scientific worldviews from turning into unexamined orthodoxy. The quote reflects Hardin’s broader habit of using provocative, evolutionary or ecological metaphors to discuss social and intellectual dynamics.