Supposing his tastes to be scholarly, and a college and professional career to be chosen, the time has come for slight changes in the system of diet,--very slight, however. It has become a popular saying among thinkers upon these questions, "Without phosphorus, no thinking;" and like all arbitrary utterances it has done more harm than good. The amount of phosphorus passing through the system bears no relation whatever to the intensity of thought. "A captive lion," to quote from Dr. Chambers, one of the most distinguished living authorities on diet, "a leopard, or hare, which can have wonderfully little to think about, assimilates and parts with a greater quantity of phosphorus than a professor of chemistry working hard in his laboratory; while a beaver, who always seems to be contriving something, excretes so little phosphorus that chemical analysis cannot detect it." Phosphatic salts are demanded, but so are other salts, fat, and water; and the dietaries that order students to live upon fish, eggs, and oysters, because they are rich in phosphorus, without which the brain starves, err just so far as they make this the sole reason,--the real reason being that these articles are all easily digested, and that the student, leading an inactive muscular life, does not require the heavy, hearty food of the laborer. The most perfect regimen for the intellectual life is precisely what would be advised for the growing boy: frequent _small_ supplies of easily-digested food, that the stomach may never be overloaded, or the brain clouded by the fumes of half-assimilated food. If our boy trains for a foot-race, rows with the college crew, or goes in for base-ball, his power as a brain-worker at once diminishes. Strong muscular action and development hinder continuous mental work; and the literary life, as a rule, allows no extremes, demanding only mild exercise and temperance as its foundation-stones. But our boy can well afford to develop his muscular system so perfectly that his mild exercise would seem to the untrained man tolerably heavy work.