Three chief evils that hang over us are disease, old age, and death. To study and control senescence, Metchnikoff proposed the establishment of a new scientific discipline he named 'gerontology.' In this classic text on the prolongation of life, Metchnikoff suggests that science should be encouraged and helped in every possible way in its task of removing the diseases and habits that now prevent human life from running its normal course, and his belief is that, were the task accomplished, the great cause of pessimism would disappear. Metchnikoff was able to proclaim himself an optimist, and found, in biological science, for the present generation a hope, or at the least an end towards which to work, and for future generations a possible achievement of that hope." From the Introduction by Gerald Gruman, MD, PhD"