The text discusses the process of moving fine substances through intricately twisted threads similar to distillers' methods. Only the finest components of blood can pass through long folded brain tubes, serving different mental functions. The passage highlights the relationship between the brain structures and the flow of spirits or fluids, comparable to how the heart manages blood.
Human Figures, Etc.
Branches are made, very skillfully twisted together, so intricately that without thousands of turns, they would be infinitely longer. One can think lightly about what passes through these intricately twisted fine threads, which not only must be very fine and light but also must be moved strongly to complete their path. This can be somewhat understood if one considers that distillers, when they want to extract a very pure and volatile spirit, do so through a pipe that winds like a Z. Only something extremely thin and volatile can rise through it, unlike water, which, due to its heaviness, cannot. Therefore, it is not hard to understand why only the finest substances of the blood, which can be moved most forcefully, can pass this long way of bent brain pipes, while the rest is forced to stay behind. Thus, the best minds today think that the true separation of the spirits could exist here. When they are separated in the bark of the brain, they pass through the pipes of the previously mentioned brain marrow, distributed and broken through numerous bends and curves, so that they may be controlled from different directions. This propulsion of spirits should be sought in the rising fluid itself, which is driven out of the heart with great force. Analysts commonly identify four recognizable cavities in the brain. These serve the aforementioned spirits, just as the heart serves the blood, where the spirits originate from.