The Science of Working Out the Body and the Soul: How the Art of Exercise Was Born, Lost, and Rediscovered

“A history of exercise is not really — or certainly not only — a history of the body. It is, equally, perhaps even primarily, a history of the mind.”

“And if the body were not the soul, what is the soul?” wondered Whitman two years before he wrote a manual on “manly health and training” and two decades before he recovered from his paralytic stroke with a rigorous exercise regimen in the gymnasium of the wilderness.

But this natural equivalence, as obvious as it was to Whitman and as evident as...