But it is to be remarked, that in the internal organs, the sentiment produced by the affection of a part is always an unfaithful index of the seat and extent of such affection. For example, hunger must undoubtedly affect the whole of the stomach, but the sensation of hunger is transmitted to us only by the cardia. A large inflamed surface in the pleura for the most part gives rise to a pain, which is felt only in a point. How often does it happen that in the head or the abdomen a pain which is referred but to a very limited space coincides with a largely disseminated affection, with an affection possessing even a different seat from that which is presumed. We should never consider the place to which we refer the sentiment as a sure index of that which the affection occupies, but only as a sign that it exists either there or thereabouts. From all this it follows, that to form a judgment of the organ, to which such or such a passion relates, we ought to recur to the effect produced in the functions of the organ by the influence of the passion, and not to the feelings of the patient. In setting out from this principle it will be easy to see, that it is sometimes the stomach and alimentary canal, sometimes the sanguiferous system, sometimes the viscera belonging to the secretions which experience a change. I shall not repeat the proofs of this assertion, but supposing it to be demonstrated, I shall assert that there does not exist for the passions as there does for the sensations a fixed and constant centre; that on the contrary the liver, the lungs, the spleen, the stomach, and the heart, are turn by turn affected, and at such time form that epigastric centre so celebrated in modern works; and if in general we refer to this region the sensible impression of all our affections, the reason is that all the important viscera of the organic life, are there concentrated. In fact, if nature had separated these viscera, had the liver for instance been placed in the pelvis, and the stomach in the neck, the heart and spleen remaining as they now are seated, in such case the epigastric focus would disappear, and the local sentiment of our passions vary according to the part affected. In determining the facial angle, Camper has thrown much light upon the proportion of intelligence enjoyed by the several classes of animals. It appears that not only the functions of the brain, but that all those of the animal life which are centred there, have this angle for the measure of their perfection.