Such is the classification that I made in my Lectures on Physiology; it has evidently nothing in common with any of those that are found in physiological works; and if you reflect upon it a little, it will appear I think infinitely preferable to any of them. Observe in fine, that each class and each order have general and characteristic attributes that particularly distinguish them, and which being applicable to all the functions of that order, mark a difference between them and all the functions of any other order. I have pointed out moreover the distinctive attributes of animal and of organic life; I have shown that the organs of one are symmetrical, those of the other irregular; that there is a harmony in the functions of the first, a discordance in those of the second; that one commences sooner and terminates later, &c. I have demonstrated, that the cerebral nerves belong especially to animal life, the nerves of the ganglions to the organic, which appears to me to be a remarkable difference, and which has induced me to make two systems of the nerves, that anatomists have united in one. The first, belonging to animal life, is composed of the cerebral nerves, the other to organic, is formed of the nerves of the ganglions, or what is commonly called the great sympathetic. But it is the vital powers especially that distinguish one life from another. I have shown that one kind of sensibility and contractility belongs to animal life, and another to organic. Now as these vital properties are the principle of the functions, it is evident that the division of these properties demonstrates that that of the two lives is not an abstraction, but that it is nature herself that has fixed the limits, since she has made particular properties for each. It is impossible to form a precise idea of the vital properties, without admitting the division I have made. How many disputes there have been, upon the subject of sensibility! Not one of them would have taken place, if the attributes of animal life had been properly distinguished from those of the organic. Certainly no one will hereafter confound in one view, as frequently has been done, the faculty that the heart has of being sensible to the entrance of the blood, without transmitting that impression, and the faculty that the skin, the other senses, the nerves, &c. have, not only of feeling the impression of external bodies, but of transmitting it to the brain, so that the sensation may be perceived. If you include under one common name of irritability, the motions of muscles that contract only by stimuli, and those which the cerebral influence puts in action, it is impossible that you should be understood.