Mailer on Ali:

Now it was as if Ali carried the idea to some advanced place where he could assimilate punches faster than other fighters, could literally transmit the shock through more parts of his body, or direct it to the best path, as if ideally he were working toward the ability to receive that five-punch combination (or six or seven!) yet be so ready to ship the impact out to each arm, each organ and each leg, that the punishment might be digested, and the mind remain clear. It was a study to watch Ali take punches.