Respect for the bodies of the dead was a religious observance in all Greece, and prevented the dissection of the human body. Consequently the knowledge of anatomy possessed by Hippocrates must have been meagre. Nevertheless,{021} he described lesions, like wounds of the head, of the heart, the glands, the nature of bones, etc. It being impossible to establish a physiology without an anatomical basis, it is not strange that we find but little physiology in the Hippocratic writings, and that this little is very crude and incorrect. Arteries and veins were confounded, and nerves, tendons, ligaments, and membranes were represented as analogous or interchangeable tissues. The physiologists of those days abandoned themselves to transcendental speculation concerning the nature and principles of life, which some placed in moisture, others in fire, etc. Speculation, thus run wild, prevented such accurate observation as might have greatly enhanced the progress of physiological knowledge. Hippocrates wrote at least three treatises concerning hygiene: The first, on _Airs, Waters, and Places_; the second, on _Regimen_; the third, on _Salubrious Diet_,--practically an abridgement of the preceding, in which he recommends the habit of taking one or two vomits systematically every month. The classification of diseases into internal or medical, and external or surgical, is not modern, but is due to Hippocrates; neither is it philosophic, although it is very convenient. With so little knowledge of physiology and pathology as the ancients had, it is not strange that they ascribed undue importance to external appearance; in other words, to what has been termed _semeiotics_, which occupies a very considerable place in the medical treatises of the Asclep-iadæ. Indeed, the writings on this subject constitute more than one-eighth part of the entire Hippocratic collection. To prognosis, also, Hippocrates ascribed very great importance, saying that "The best physician is the one who is able to establish a prognosis, penetrating and exposing first of all, at the bedside, the present, the past, and the future of his patients, and adding what they omit in their statements. He gains their confidence, and being convinced{022} of his superiority of knowledge they do not hesitate to commit themselves entirely into his hands. He can treat, also, so much better their present condition in proportion as he shall be able from it to foresee the future," etc.