The text discusses the phenomenon of sleep, explaining how the body's functions slow down, and new "spirits" rejuvenate the person during rest. It notes that the quality of sleep is influenced by the food consumed and describes how a person's posture affects the ease of falling asleep, with lying down being more beneficial than sitting upright. Finally, it elaborates on the process of waking as these renewed spirits activate the body.
Actual Phenomena
The phenomena where humans fall into a state of unconsciousness. When a person falls asleep due to a reduction of spirits, temporarily the circulation of blood and other functions slow down; meanwhile, new spirits are prepared again, which when strong enough can pierce through again, that is, from marrow through the nerves into the muscles of the body; then a person begins to wake up, stretches out, and all parts of the body are properly activated. Thus, once fully awake, they are capable of setting their body steadily on their feet and going to work. Now, whether a person sleeps longer during one time than another often depends on the food and drink consumed, as some are digested easier than others, subsequently affecting the slackening or arousal of the spirits, causing delay or alertness. From this, we can understand why many people, sitting upright or on a chair, find it more difficult to sleep as comfortably as lying on a soft bed. Sitting requires more influence of spirits to keep the body’s muscles filled and strong enough to maintain that posture. Consequently, sitting does not bring stillness as readily as lying down, supported by a bed, mattress, or bench; as no more spirits are needed for mere sustenance, which is for breathing. Therefore, completely asleep people are very deeply asleep.
How and why a Sleeping Person Awakes.
Someone can sleep lying much more soundly than sitting.