I’ve been happily married for almost 18 years, but my kids listen to enough Taylor Swift (Lord help me) for me to know what a broken heart means in 21st-century America: It means “breaking down and coming undone,” feeling that “I’m only me when I’m with you” (don’t get me started on how messed up this is), and sopping up the “teardrops on my guitar” (Taylor Swift lyrics).
Maybe what Taylor needs is a good dose of 17th-century medical inquiry. How did you know when your heart was broken? When it stopped beating. Probably because of a plague.
For a more nuanced understanding of the workings of the heart, we owe a debt of gratitude to physician and natural philosopher William Harvey, who is credited with “discovering” the circulation of the blood. Harvey was the first to systematically describe the action of the heart and the circuitous motion of the blood in the body.
Before Harvey, most physicians followed 2nd-century Roman physician Galen, who theorized that the heart’s role was to produce the body’s heat: venous blood came from digested food that was “cooked” in the liver and imbued with vital spirit. Other parts of the body sucked up this blood for nourishment. Some of the blood that went to the heart passed through the ventricular septum, where it was further refined and mixed with “inspired air” from the lungs. This new concoction was the arterial blood, also used for nourishment.
One critical problem for 17th-century doctors, however, was that medical schools favored a model of dissection in which the professor merely read anatomical texts; a hired anatomist (sometimes, if not often, himself illiterate) did the actual dissection. So the anatomy professor did not always realize that what was in the text was not what could be found in the body itself.
Harvey, who insisted on performing dissections himself, observed that the heart simply does not behave the way the textbook said it would. Nor, to his aggravation, could he find any proof that ventricular blood could pass through the septum.
Another vexing problem for Harvey was how the blood could circulate around the body without reversing direction, pooling in the hands and feet. This was cleverly solved, however, by considering a discovery made by his professor at Padua, Hieronymus Fabricius, that veins had valves that could stop the flow of blood. Harvey relied on a beautifully simple experiment to show the function of the veins: you can see it in the video below from 23:16-24:55Do be careful, however, as the rest of the video has much blood and organ stuff.
Here, also, is a picture of the experiment.
So, play along at home, my friends! Try these experiments: if your blood does not flow in the correct direction, likely your heart is broken. But if the experiment is successful, your heart is in fine working condition and primed to have a very happy Valentine’s Day.
Edited to add: I told my daughter about this post, and she sent me this meme to share with you all. We are clearly a family of literalists.