Actually, my solution generated considerable further work and the "dog-flea" model keeps cropping up from time to time in unexpected contexts. - Mark Kac

I then reached for a time honored tactic used by mathematicians: if you can't solve the real problem, change it into one you can solve.

I prefer concrete things and I don't like to learn more about abstract stuff than I absolutely have to.

There was hardly a page in Markov's book which did not feature the normal law and it cast a spell over me from which I have never fully recovered. Adding to the fascination was the impression that somehow the normal law was the key to mysterious and elusive world of chance phenomena.