The Notebooks of Leonardo Da Vinci Complete


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8
49.  
The waters return with constant motion from the lowest depths of the  
sea to the utmost height of the mountains, not obeying the nature of  
heavier bodies; and in this they resemble the blood of animated  
beings which always moves from the sea of the heart and flows  
towards the top of the head; and here it may burst a vein, as may be  
seen when a vein bursts in the nose; all the blood rises from below  
to the level of the burst vein. When the water rushes out from the  
burst vein in the earth, it obeys the law of other bodies that are  
heavier than the air since it always seeks low places.  
[Footnote: From this passage it is quite plain that Leonardo had not  
merely a general suspicion of the circulation of the blood but a  
very clear conception of it. Leonardo's studies on the muscles of  
the heart are to be found in the MS. W. An. III. but no information  
about them has hitherto been made public. The limits of my plan in  
this work exclude all purely anatomical writings, therefore only a  
very brief excerpt from this note book can be given here. WILLIAM  
HARVEY (born 1578 and Professor of Anatomy at Cambridge from 1615)  
is always considered to have been the discoverer of the circulation  
of the blood. He studied medicine at Padua in 1598, and in 1628  
brought out his memorable and important work: De motu cordis et  
sanguinis.]  
8
50.  
697  


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