Hippocrates, although Galen affirms that he was not entirely unacquainted with the pulse, does not appear to have attached much importance to the observation of it, for he generally neglects to mention its characters, where we would most expect to find them stated, as, for example, when he is detailing the symptoms of epidemical fevers. Celsus, too, expresses himself in doubtful terms respecting the indications furnished by the pulse: “Venis enim maxime credimus, fallacissimæ rei; quia sæpe istæ leniores, celerioresve sunt, et ætate, et sexu, et corporum naturâ; et plerumque satis sano corpore, si stomachus infirmus est, nonnunquam etiam incipiente febre, subeunt et quiescunt; ut imbecillus is videri possit, cui facile laturo gravis instat accessio. Contra sæpe eas concitat et resolvit sol, et balneum, et exercitatio, et metus, et ira, et quilibet alius animi affectus.” Aretæus and Cælius Aurelianus are indeed sufficiently minute and accurate in detailing the characters of the pulse, while describing the symptoms of various diseases, but neither of them has written expressly on the subject; and, as the works of Herophilus, Agathinus, Magnus, Athenæus, and Archigenes are entirely lost, Galen must be considered as our first and great authority on the pulse—we might almost have said our sole authority, for all subsequent writers were content to adopt his system, without the slightest alteration. As our author’s account of the subject is professedly taken from the elaborate treatises of Galen, it may, perhaps, appear unnecessary to attempt any further exposition of the system; but the importance of the subject, and, we may add, its novelty to modern readers, have induced us to make some detached observations upon it, in order to explain some parts of it which are confessedly obscure, and to answer certain objections which have been stated against it, by modern writers who have not properly understood its principles. We shall first notice the objection stated to Galen’s Theory of Respiration by Van Helmont, who, although compelled to admit the ingenuity of Galen’s system, pretends to differ from him respecting the final cause of arterial action and respiration, which, he maintains, is not refrigeration, but the maintenance of animal heat. (Opera, p. 112.) But if he had read Galen’s work ‘de Usu Respirationis’ carefully, he would have found that this is the very sense which Galen attaches to the terms refrigeration and ventilation. Van Helmont states, as a new discovery, that a sort of concoction of the blood takes place in the left ventricle of the heart. But he might have found this doctrine also in the works of Galen. According to Galen, the pulse consists of four parts: of a diastole and a systole with two intervals of rest, one after the diastole before the systole, and the other after the systole before the diastole. He maintains that by practice and attention all these parts can be distinguished. (De Dignos. Puls. iii, 3.)