De somno et vigilia theses ad disputandum propositae

It is beyond controversy that an animal is awake while it exercises the functions of the senses, and that it is deprived of the function of the senses during sleep.

II.
From the law of opposites, it is also settled and fixed: the subject of both is the same, namely that by which an animal is said to perceive; and therefore, both sleep and waking are an affection not of this or that part, but of the animal itself.

III.
From this it follows that waking is an affection of the animal by which, while present, it can perform external sensations; but sleep is that by which the actions of these same senses cease.

IIII.
This notion opens a path to investigating the causes that produce sleep and waking. For just as those things that are required for sensation are correctly established as the causes of waking, so their deprivation is not undeservedly believed to produce sleep.

V.
Both common causes for all, and proper causes for individual sensations, concur toward these sensations.

VI.
The common ones are the faculty, the proper organ itself, that is, the animal spirits and the cavities and pathways through which the spirits and the faculty move and flow; and finally, the innate heat original: "calidum innatum", the common instrument of the soul, which by its motion and presence brings the aforementioned spirits—as the proper and immediate causes of all other actions—into act.