In the brain centers that preside over language there is continuous development, so that it has been carefully estimated that our powers of expression culminate between 45 and 55. Demosthenes’ _De Corona_, his masterpiece, was delivered at the age of 52; Burke’s impeachment of Hastings, when he was 58; and many authors have thought their vocabulary and command of language at its best during this decade. After this, faint symptoms of aphasia and amnesia begin to show themselves. But it is in the frontal lobes, in which it is now believed that the powers of attention, reason and judgment are located, that the acme of development comes still later, perhaps in the decade ending at the age of 65. Indeed, Moebius and others have shown that the cortical layers believed to be most closely associated with mentation are still developing as late as the age of sixty-three. Bacon produced the first two books of the _Novum Organum_ at 59; Kant’s _Critique of Pure Reason_ was produced when he was 57; Harvey’s great work on the circulation, when he was 72, etc. It is certain that long after memory of names and physical vigor have begun to abate, the power of comparison, inference, and above all a moral sense, which is perhaps the finest and latest of all our powers, comes to full maturity. The ideal of a greater old age is not an idle dream and Browne insists that physicians should strive themselves to live to be 100 and to make their patients do so. The best antiseptic against senile decay is, he thinks, active interest in human affairs. This, at any rate, should be our working hypothesis. A man of 80 should realize that he has one-fifth of his life before him. He tells us of a man of 84 who attempted suicide because he could no longer support his parents, and of another of 102 who had undergone a successful operation for cancer of the lip without anæsthetics. Of course, senile involution, when cell growth is more than counterbalanced by cell decay, is the natural pathway to death, and a man ultimately dies of it when there is no question of disease. But the brain, like the lens of the eye, may become flatter and more longsighted, focusing better on objects far than those that are near. There is no short cut to longevity. Its achievement must be the work of a lifetime. Sympathy, which goes far deeper than courteous manners, is fundamental for the successful treatment of old age.