Michael Williams was recently persuaded to give a semi-public talk on the subject before an audience of several hundred professional and business people. He was compelled to spend the rest of the evening in answering the questions of his audience; and listening to these questions, I was made to realize the tremendous interest of the public in the practical demonstration which Mr. Horace Fletcher has given of the idea of Metchnikoff, that men and women to-day grow old before they ought to do so, and that the prime of life should be from the age of fifty to eighty. A broken-down invalid at forty-five, Mr. Fletcher was at fifty-four a marvel of strength—and at fifty-eight he showed an improvement of one hundred per cent. over his tests at the age of fifty-four; thus proving that progressive recuperation in the so-called “decline of life” might be effected by followers of the new art of health. As a result of this address, Williams was invited by the president of one of the largest industrial concerns in the country to lecture to his many thousands of employees on the new hygiene; his idea being to place at their disposal the knowledge of this new method of increasing their physical and mental efficiency. For business men and women, indeed, for workers of all kinds, good health is capital; and the story of the new hygiene is the story of the throwing open of hitherto unsuspected reserve-stores of energy and endurance for the use of all. In writing upon this subject, the experiences most prominent in our minds have naturally been those of ourselves, of our wives and children, and of friends who have followed in our path. As the setting forth of an actual case is always more convincing than a general statement, we have frequently referred to these experiences, and what they have taught us. We have done this frankly and simply, and we trust that the reader will not misinterpret the spirit in which we have done it. Mr. Horace Fletcher has set the noble example in this matter, and has been the means of helping tens of thousands of his fellow men and women. [Illustration: MR. UPTON SINCLAIR AND MR. MICHAEL WILLIAMS Resting from their favorite exercise.]