As there are some twenty-four pairs of these in an area only slightly greater than that of the outspread hand, and as they are capable of acting with every imaginable grade of vigor and in every possible combination, it can readily be seen what an infinite and complicated series of expressions--or, in other words, indications of the state of affairs within those different orifices--they are capable of. Only the barest and rudest outlines of their meaning and principles of interpretation can be attempted. To put it very roughly, the main underlying principle of interpretation is that we make our first instinctive judgment of the site of the disease from noting which of the three great orifices is distorted furthest from its normal condition. Then by constructing a parallel upon the similarity or the difference of the lines about the other two openings, we get what a surveyor would call our "lines of triangulation," and by following these to their converging point can often arrive at a fairly accurate localization. The greatest difficulty in the method, though at times our greatest help, is the extraordinary and intimate sympathy which exists between all three of these groups. If pain, no matter where located, once becomes intense enough, its manifestations will travel over the face-dial, overflowing the organ or system in which it occurs, and eyes, nostrils, and mouth will alike reveal its presence. Here, of course, is where our second great process, so well known in all clew-following, elimination, comes in. A patient comes in with pain-lines written all over his face. To put it very roughly--has he cancer of the stomach? Pneumonia? Brain tumor? If there be no play of the muscles distending and contracting the nostrils with each expiration, no increased rapidity of breathing, no gasp when a full breath is drawn, and no deep red fever blush on the cheeks, we mentally eliminate pneumonia. The absence of these nasal signs throws us back toward cancer or some other painful affection of the alimentary canal. If the pain-lines about the mouth are of recent formation, and have not graved themselves into the furrows of the forehead above and between the eyebrows; if the color, instead of ashy, be clear and red, we throw out cancer and think of colic, ulcer, hyperacidity, or some milder form of alimentary disease.