cure, but not to employ new ones, however well he may think of them, until repeated experience and observation have proved their fitness and value. It follows that he who practises honestly his profession in private life only, can very rarely have anything new to advance; he has devoted his life to studying carefully all that has been proposed for the relief of disease, he has selected his means cautiously, and often employed them successfully, but he has probably never originated anything. He can confirm or confute the observations of others, and give a sound opinion as to their relative value; but his life is passed in using the means prepared to his hand, not in seeking out new ones. His may be a less brilliant career than that of the inventive genius, but it is one of real utility. Here, as in all cases, the division of labour is important, and leads to good results; and hence it is that often very able practical physicians and surgeons, to whose ability and skill all bear witness, are nowise distinguished as discoverers, and but little known as authors.

Such men, in estimating the value of the means at their command, employ a line of reasoning as strictly

The opinions I have stated above wald are PEstrained me from appearing before the pair as a writer on any object except on the one I have chosen. for I have not vanity enough to imagine that I am better acquainted with the nature of disease, or the modes of cure, than my professional brethren: nor have I anything to state to them of great novelty or value; but it has seemed strange to me how little attention appears to be paid to the conduct of life with a view to avoid disease, to preserve sound health, and to lengthen out, in happiness and enjoyment, the period of our earthly career. It seems as if physicians, content with combating disease when it appears, concern themselves but little about the means of preventing its approach. It is surprising how little has been written on this subject, and yet how desirable it is

that it should be understood. If good health and length of life be blessings we all justly desire to enjoy, he will surely perform a welcome service to his fellowmen, who shall point out how to attain the one and to preserve the other. They are benefactors to mankind who teach how to combat the attacks of disease, and to restore the injured organisation to a naturally sound condition; but it is better still to keep the body in so sound a state as to defy disease, and enable men to pass through life from year to year in healthful and vigorous activity. I dare not hope that I have succeeded in showing how to do this, but I have endeavoured to do something towards so great an end.

This book is, indeed, merely an essay towards a great and highly important object,-an essay which

'I do not mean that the subject of Hygiene has been wholly neglected. The works of Drs. J. Johnson, S. Smith, Hodgkin, Dunglison, Tilt, Day, and of Messrs. Mayo and L. Beale, and others, contain much that is valuable; but, except the work of M. Revielle Pariset referred to in these pages, I do not know of any distinct Essay on the means of promoting Longevity, since Hufeland published about 65 years since Die Kunst das menschlische leben zu verlängern,'-(The Art of prolonging Human Life,) which has been twice well translated into English.

may be enlarged and improved in future, which may, perhaps, call attention to the subject, and induce abler men to examine into it. I shall really rejoice if it should be so, and if this slight attempt should be the cause of calling the attention of the medical profession and the public to the investigation of the best means of preserving health and inducing longevity, I shall hope that I have, as far as in me lies, followed out the advice of the sage Heberden, and fulfilled the duties of my vocation.

There can be no doubt that health is the natural condition of man, and that we ought to pass through life in a state of vigour, enjoying every day of our existence. It is imperiously our duty to study the best means of promoting so happy a condition. If we thank the Great Creator of all for the life he has bestowed on us, we should endeavour to retain His gift in its fullest perfection. It would be well for mankind if the principles of Physiology, and the laws of Hygiene as deduced therefrom, formed a part of every course of education; for then men, being acquainted with the great causes of disease and the best means of preserving health, would so conduct themselves as to

secure the one and avoid the other; and, if at any time the evil did appear, they would not become an easy prey to the unscrupulous effrontery of the ignorant charlatan, but, reflecting on the complicated structure and varied functions of the animal machine, they would well understand that he only who fully comprehends its actions in health can venture to guide and to restore them when their due course has been deranged by some baneful influence: cupidity and effrontery are the parents of quackery; but it is ignorance or timidity that leads its dupes into the snare.

It is well to study not only how to live healthily, but also how to live long. Let it not be said that we are unable to do this-that the duration of life is nowise in our power, and that we cannot lengthen it a single day: this is wholly untrue. There is, probably, no fixed limit to our existence; and even if there were, how few attain it! How few really die of old age! Parr's death at 152 was premature-induced by a foolish change from the simple diet and active habits of a peasant to the luxurious ease and exciting foods and drinks of a courtly gentleman. His body was examined