pulse is rendered stronger by passion and baths, not being naturally so. In reply to which, Galen contends that a pulse rendered stronger by non-natural causes soon undergoes a change; and that, therefore, a strong pulse, which does not readily change, may be natural and moderate. The fourth kind is in regard to the consistence of the instrument, I mean the body of the artery. In this respect there are three differences; for the artery is either harder than natural, and is called a _hard_ pulse; or softer, and is called a _soft_, or intermediate, and is called in this respect _moderate_. The fifth kind is in regard to the contents of the artery; and their differences are, the _full_, the _empty_, and the _moderate_, since every vessel must be full, empty, or moderately full of liquids. A full pulse, then, as Archigenes defines it, is one which indicates an artery that is completely full, and the impression of which is, that it is distended with fluids; and an empty one conveys an impression as if its contents were full of bubbles of air, so that the finger, when pressed upon it, seems to fall into an empty space. These five kinds of pulses regard one motion of the artery. And since the quality of the heat in the heart may be more developed than usual in the artery, some have hence reckoned a sixth kind of pulses. Of the other kinds, whether they are in regard to one or more pulsations, they derive their character either from the time of rest, or the rhythm, or their equality and inequality, or their regularity and irregularity. The kind, then, in regard to the time of rest, which is the seventh in order, is divided into the _dense_, the _rare_, and the _moderate_. And, since an artery has a double motion, composed of two opposite movements, it must of necessity have two seasons of rest: the one after the diastole before the systole, the other after the systole before the diastole, which to most people appears imperceptible; and, therefore, the interval of rest between two motions has been chosen. When, therefore, there is a long interval of rest, the pulse is called _rare_; when short, _dense_; and when intermediate, _moderate_. The eighth kind is in respect to rhythm. Rhythm, then, in general, is the ratio and proportion of one time to another. In regard to the pulse, it is, according to some, the ratio of the time of motion to the time of rest, as of the systole and diastole, to the intermediate time of rest; but, according to others, it is the ratio of a time of motion and rest to another time of motion and rest, or of motion to motion.