Facing my critics, lay and professional, I wish at the outset to disclaim the methods by which Sol invigorated the casual amateur. I am not prophesying unlimited sunshine for every one, without regard to conditions. In this book no mention will be found of royal roads, panaceas, or grand specifics. I have attempted rather to treat every reader as Sol treated his intimates. I have looked into the sky and made a careful survey of the horizon. It is true that I have seen an ideal and the promise of its fulfilment, but my deductions have been drawn with patient care from signs which I have studied with diligence; if I am an optimist, it is because I see the promise of fair weather, and not because I wish to delude the unwary. And with this I will lay down my metaphor and come to a practical statement. I know that I shall be regarded in many quarters as a revolutionary and a heretic, for my theory and practice, though founded on a principle as old as the life of man, are not in accord with, nor even a development of, the tradition which still obtains. But in thus rejecting tradition I am, happily, sustained by something more than an unproved theory. Moreover, on this firm ground I do not stand alone. Though my theory may appear revolutionary and heretical, it is shared by men of attainment in science and medicine. On a small scale I have made many converts, and in now making appeal to a wider circle I am upheld by the knowledge that what I have to say can no longer be classed as an isolated opinion. Not that I should have hesitated to come forward now, even if I had been without support. During the past thirteen years I have built up a practice in London which has reached the bounds of my capacity. This work has not been done by any advancement of a wavering hypothesis. I have had cases brought to me as the result of the failure of many kinds of treatment, of rest cures, relaxation cures, hypnotism, faith cures, physical culture, and the ordinary medical prescriptions, and in the treatment of these cases, in my own observations, and in the appreciation of the patients themselves, I have had abundant opportunity to prove to my own satisfaction that in its application to present needs my theory has stood the test of practice in every circumstance and condition.