The circulatory system, as William Harvey imagined it

In ancient (Galenic) medicine, it was the liver that creates blood from the lacteals that deliver nutrients from the intestines. Then the inferior vena cava arises from the liver and delivers blood to the right side of the heart. It then goes to the lungs through the pulmonary arteries to "feed" them.

At the same time, the ancients believed, there were invisible pores in the septum of the heart which allow blood to seep through to the left side of heart. There, the pulmonary veins deliver "spirit" or vital air from the lungs to the heart where it gets mixed with blood in the left ventricle (and this explains the bright red color of arterial blood). Afterwards, the blood travels to the rest of the body through the aorta. Once it reaches its destination, it gets "consumed" by the organs of the body, so the liver has to make more blood, and so on ad infinitum.

Shit was weird

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Baghdad,
As seen from the ISS on July 18th

Leviathan,
A book by Thomas Hobbes

The Destruction of Leviathan,
By Gustave Doré

On the question of being understandable—
One does not only wish to be understood when one writes; one wishes just as surely not to be understood. It is not by any means necessarily an objection to a book when anyone finds it impossible to understand: perhaps that was part of the author’s intention—he did not want to be understood by just ‘anybody.’ . . . All the more subtle laws of any style have their origin at this point: they at the same time keep away, create a distance, forbid ‘entrance,’ understanding, as said above—while they open the ears of those whose ears are related to ours.

- The Joyful Science, aphorism 381

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Believers and their need to believe—
The extent to which one needs a faith in order to flourish, how much that is 'firm' and that one does not want shaken because one clings to it - that is a measure of the degree of one's strength (or, to speak more clearly, one's weakness). Christianity, it seems to me, is still needed by most people in old Europe even today;
hence it still finds believers. For that is how man is: an article of faith could be refuted to him a thousand times; as long as he needed it, he would consider it 'true' again and again

Even the vehemence with which our cleverest contemporaries get lost in pitiful nooks and crevices such as patriotism (I refer to what the French call chauvinisme and the Germans 'German'), or in petty aesthetic creeds such as French naturalism (which enhances and exposes only the part of nature that simultaneously disgusts and amazes), or in Petersburg-style nihilism (meaning faith in unbelief to the point of martyrdom), always indicates primarily the need for faith, a foothold, backbone, support.