# The Generation of the Heart and the Brain

In the other branch of that vein, blood is collected, and it is from this that the liver is first formed. From this, it is perfectly clear that the liver is essentially nothing more than congealed blood. In the other branch, those textures of the veins are generated alongside the expansion of other vessels; thus, all the veins are traced back to a single trunk in the upper part of the liver—namely, the vena cava.

Then the heart, along with its own vessels, is produced by the action of the vital force in the following way: the veins draw in the warmest and most refined blood, from which the heart—naturally fleshy and thick—is generated in its earliest stage. Here, the aorta is also observed, which gives rise to all the other arteries that diffuse the vital spirit throughout the entire body. Since veins erupt from both cavities of the heart and are inserted into the lungs, the lungs are also created from these. Indeed, the vein proceeding from the right cavity of the heart produces a very refined blood which, as its fibers are dispersed here and there, is easily transformed into the substance of the lung. Moreover, from the great vessels of the heart and liver—specifically the vena cava and the aorta—not only the entire chest but also, subsequently, the legs and arms are generated.

Furthermore, within the same timeframe, the principal part of the human structure—the brain—is created within the third membrane of this mass. It becomes filled with "animal spirit," which draws a significant portion of the reproductive fluid into a certain cavity where the brain takes shape. It is then enclosed all around by a sort of lid that, once dried, becomes the skull, as can be seen in the two accompanying figures.