He holds that the teeth must be enumerated among the bones, and does not admit any doubt to be raised on this point, as these parts can be looked upon neither as cartilages, nor as arteries, nor as veins, nor as nerves, nor as muscles, nor as glands, nor as viscera, nor as fat, nor as hair—a method of reasoning by elimination which is very specious but far too weak! Galen indicates exactly the number of incisor, canine, and molar teeth (without, however, making any distinction between small and large molars), and speaks of the different functions of these three kinds of teeth. Not always, he says, are the molars of each jaw five in number on each side; in some individuals there appear only four; in others six. The incisors and canines have but one root; the upper molars have generally three, but sometimes, though not often, four; the lowers have for the most part two, rarely three. Galen is the first author who speaks of the nerves of the teeth. He says that these organs are furnished with soft, that is sensitive, nerves[179] belonging to the third pair.[180] The teeth, according to him, are furnished with nerves, both because, as naked bones, they have need of sensibility, so that the animal may avoid being injured or destroyed by mechanical or physical agencies, and because the teeth, together with the tongue and the other parts of the mouth, are designed for the perception of the various flavors.[181] In regard to odontalgia, Galen made some very important observations on his own person: “Once when I was troubled with toothache, I directed my attention to the seat of the pain, and thus I perceived very clearly, that not only was the tooth painful but also pulsating, which is analogous to what happens in inflammations of the soft parts. To my astonishment, I had to persuade myself that inflammation may arise even in a tooth, in spite of the dental substance being hard and lapideous. But another time, when I again was attacked by odontalgia, I perceived very distinctly that the pain was not localized in the tooth, but rather in the inflamed gums. Having, therefore, suffered these two kinds of pain, I have acquired the absolute certainty that, in certain cases, the pain is situated in the gums, in others, on the contrary, in the very substance of the tooth.”