De Motu Animalium

which the muscle had been attached ceases entirely, while the action of the same joint, which depends on other muscles terminating there, remains meanwhile unharmed.

Likewise, it is known that a musculum muscle is a machine inert and dead in itself, unless the facultas motiva motive faculty arrives from without, which brings the command and rouses it from sleep and torpor and impels it to motion. This is because, during sleep and rest, the muscle of the elbow, for example, even if it is whole and unharmed, does not move the arm unless it is impelled by the appetitus appetite to exercise the action.

But it has been questioned until now by what way and through which conduits the imperium animæ command of the soul and the facultas motiva motive faculty are carried to the musculum muscle. However, sense and experience have easily revealed this. For since arteriæ, venæ & nervi arteries, veins, and nerves lead to the muscle from outside, our elders proved by this reasoning that this duty is not owed to the veins or arteries: that if a vena vein or arteria artery were tied or severed, the facultas motiva motive faculty should not be carried to the muscle, the passage and way having been closed or removed; and yet it has been observed that the musculum muscle exercises its motions no less than when the aforementioned vessels were intact. From this it is concluded that the motiva facultas motive faculty is not transferred through the venas, aut arterias veins or arteries to agitate the muscle. On the contrary, when the nervus nerve—which terminates and is inserted into some muscle—is severed or tightly ligated, the motion and agitation of that musculi muscle cease entirely, and it remains entirely inert and, like a corpse, immobile. Wherefore the nervus nerve is the conduit through which the facultas motiva motive faculty is communicated to excite, move, or convey, so to speak, the imperium animæ command of the soul to the musculo muscle, so that it may be moved and agitated. But what is carried through the nervos nerves to the muscle—whether it is an facultas incorporea incorporeal faculty, or an aura breeze, or a flatus breath, or some succus juice, or a certain motio motion, or impulsus impulse, or something else, and by what reason it can overcome the resistance of huge weights,