De causis curatricibus Theses Progymnasticae

LIV.
Therefore, its primary and proximate (as well as common) instrument, by which it descends into its work, is that spirituous, warm, moist, pure, and thin substance, which from the very beginnings of generation (namely, the seed) resides in the solid parts of the whole body, but especially in the heart, and is necessarily fostered, nourished, restored, excited, and actuated by another constantly generated and flowing in from the heart from thin, vaporous blood. It forms one species with it, and is called by Aristotle and Theophrastus θρμύτης γονιμὸς generative heat and σύνθα σπυίτης inborn spirit, and by Galen θρμύσε ίμφυτὸ innate heat.

LV.
Yet actions cannot be perfectly accomplished, nor can the difference and species of actions be constituted and effected, by this one solitary thing alone.

LVI.
Therefore, secondary and particular things are added: a certain temperament, and proximately from this, a certain structure or composition, comprised of magnitude, number, figure, and position. These things are also diverse in the individual parts, which makes not only the parts themselves, but also the operations that are exerted in them and through them, different.

LVII.
Thus, there are three most important organs or instruments by which this principal intrinsic Efficient Principle exhibits its motions (especially the more common ones) in the body and through it—not only whole and perfect, but also diverse and distinct: namely, innate heat and spirit, temperature, and composition.

LVIII.
The Soul produces those dissimilar actions appearing in the human body, not by reason of its own multiplex or heterogeneous substance: but first (as we were saying before) by reason of the laws and powers prescribed to it by the Creator; and second, by reason of the parts of the body in which it acts, which are diverse in both temperament and structure.

LIX.
In this way, therefore, it is the author of imagination, reasoning, and memory in the brain; of pulsation and the generation of vital spirits in the heart; of vision in the eyes; of the generation of sperm in the testicles; of walking in the feet; of sanguification in the liver and veins; and, universally, of nutrition and preservation in all.

LX.
For this reason, one soul—not at all this or that species or part of it—stirs these "conservative" motions of the body, if I may so call them, about which it was begun to speak above, through its vegetative or nutritive power, not its intellectual or sensitive power.

LXI.
And this very thing, in the schools of the philosophers, where they speak of the actions of the body, exists as that famous and frequently mentioned