PREFACE TO THE FIRST EDITION.

THE three lectures forming the first part of this volume were delivered before the Royal College of Physicians of London, to which I had the honor of being appointed Gulstonian Lecturer for this year; the latter part consists of two articles which, having appeared elsewhere, are reprinted here as presenting a completer view of some points that are only touched upon in the lectures; and the general plan of the whole, as thus constituted, may be described as being to bring man, both in his physical and mental relations, as much as possible within the scope of scientific inquiry.

The first lecture is devoted to a general survey of the Physiology of Mind-to an exposition of the physical conditions of mental function in health. In the second lecture are sketched the features of some forms of degeneracy of mind, as exhibited in morbid varieties of the human kind, with the purpose of bringing prominently into notice the operation of physical

causes from generation to generation, and the relationship of mental to other disorders of the nervous system. In the third lecture, which contains a general survey of the pathology of mind, are displayed the relations of morbid states of the body to disordered mental function. I would fain believe the general result to be a well-warranted conclusion that, whatever theories may be held concerning mind and the best method of its study, it is vain to expect, and a folly to attempt, to rear a stable fabric of mental science, without taking faithful account of physiological and pathological inquiries into its phenomena.

In the criticism of the "Limits of Philosophical Inquiry," which follows the lectures, will be found reasons why no attempt has been made to discuss the bearing of the views broached in them on any system of philosophy. Neither materialism nor spiritualism are scientific terms, and one need have no concern with them in a scientific inquiry, which, if it be true to its spirit, is bound to have regard only to what lies within its powers and to the truth of its results. It would seem to be full time that vague and barren disputations concerning materialism and spiritualism should end, and that, instead of continuing such fruitless and unprofitable discussion, men should apply themselves diligently to discover, by direct interroga tion of Nature, how much matter can do without spiritual help. Let each investigator pursue the method

of research which most suits the bent of his genius, and here, as in other departments of science, let each system be judged by its fruits, which cannot fail in the end to be the best sponsors and sureties for its truth. But the physiological inquirer into mind may, if he care to do so, justly protest against the easy confidence with which some metaphysical psychologists disdain physiological inquiry, and ignore its results, without ever having been at the pains to make themselves acquainted with what these results are, and with the steps by which they have been reached. Let theory be what it may, there can be no just question of the duty of observing faithfully all the instances which mental phenomena offer for inductive inquiry, and of striving to realize the entirely new aspect which an exact study of the physiology of the nervous system gives to many problems of mental science. One reflection cannot fail to occur forcibly to those who have pursued this study, namely, that it would have been well could the physiological inquirer, after rising step by step from the investigation of life in its lowest forms to that of its highest and most complex manifestations, have entered upon his investigations of mind without being hampered by any philosophical theories concerning it. The very terms of metaphysical psychology have, instead of helping, op pressed and hindered him to an extent which it is impossible to measure: they have been hobgoblins to

frighten him from entering on his path of inquiry, phantoms to lead him astray at every turn after he has entered upon it, deceivers lurking to betray him under the guise of seeming friends tendering help. Let him take all the pains in the world, he cannot express adequately and exactly what he would-neither more nor less-for he must use words which have al ready meanings of a metaphysical kind attached to them, and which, when used, are therefore for him more or less a misinterpretation. He is thus forced into an apparent encroachment on questions which he does not in the least degree wish to meddle with, and provokes an antagonism without ever designing it; and so one cannot but think it would have been well if he could have had his own words exactly fitting his facts, and free from the vagueness and ambiguity of a former metaphysical use.

The article on the "Theory of Vitality," which appeared in 1863, is now reprinted, with a few, mainly verbal, alterations. The aspect of some of the questions discussed in it has been somewhat changed by the progress of inquiry and thought since that time, but it appears to the Author that, great as discussion has been, there are yet considerations respecting vitality that have not been duly weighed. Whether living matter was formed originally, or is now being formed, from non-living matter, by the operation of physical causes and natural laws, are questions which, notwith.