Psychology teaches how to find the way into the darkness of a patient’s soul.  Physiognomy teaches, not only to read in the face and external appearance, the story of a life which is written there in characters which only experience may decipher, but also to realize when the patient employs physiognomical expressions to hide what we persistently seek; namely, the truth.

And again, in regard to healing, psychology teaches how to influence the patient so that he may discontinue to be his own worst enemy; that he may recognize his mistakes as such and discard them, although possibly he may have grown so addicted to his tastes as to prefer to continue therein in place of daring to be healthy.

In the plan of production of a regenerated and healthy humanity, every individual of this kind must be regarded as a foe who interferes with the prevention of disease both now and in futurity.  To win such an one over, to make him an enthusiastic believer in the theory that health is a necessity, and, a task less easy, to prevent his relapse into his previous degenerate manner of life and health,—­this is another branch of science for which psychology and physiognomy are more needful than anything else.

Here again it is the true physician’s principle to enlighten the layman, and not to surround his methods with a mysterious, but imposing wall of secrecy.

We do not hesitate to reveal the main points of our system of diagnosis, which is much broader than the old system of scholastic medicine,—­the performance with auscultation, percussion, X rays and the rest.  Certain knowledge of these things will lead every one, ere long, to submit all disturbances of health to the hygienic physician while prevention is still probable and possible, instead of waiting until disease has taken firm hold.  It will also enable men to realize that the old-school practitioner who pronounces them sound while they feel for themselves that there is something wrong within has yet “a something” left to learn.

The realm of psychology, however, is beyond the scope of my present endeavour, save in so far as it may serve to show that we are fortified with this particular knowledge, and to the end that this book may constitute a help to the aspiring hygienic-dietetic physician, calling his attention to the necessity of acquiring as profound a knowledge of psychology as may be.

I will confine myself at present, therefore, to the external symptoms which must be observed, though they are not generally considered as symptoms of disease; and yet they indicate disease or the disposition thereto, individual or hereditary, as the case may be.

I shall consequently deal with the peculiarities of hands and feet, nails and hair, eyes and ears, nose and teeth, mouth, forehead, tongue, chin, cheeks, neck, chest, abdomen, legs, and general constitution.

Nature has endowed us with strong discriminating faculties against certain external indications of disease.  We experience a pleasant feeling when the hand is pressed by another hand that is warm and dry, but we shrink from the hand that is cold and moist and clammy.