An Astonishing Circle: The Discovery and Denial of the Circulatory System

by Maria Parrott-Ryan

An ingenious discovery . . . dismissed as a dangerous lie.

In 1628, anatomist and physician William Harvey made a controversial that blood circulated continuously through the body, pumping from the heart through the blood vessels into the tissues and then returning to the heart. His research contradicted many anatomy “experts” of the time. In the seventeenth century, European physicians did not go against the ancient Greek and Roman thinkers who’d created the foundations of Western medicine. But what if those foundations were wrong?

This is the story of how humans came to understand the circulatory system. And Harvey’s work is only one part of that story. Discover the breakthroughs of scientists and scholars who dared to think outside the box, from Ibn al-Nafis, an Arab Muslim scholar who discovered pulmonary circulation; to Marcello Malpighi, who studied capillaries; to Joseph Priestley and Antoine Lavoisier, who figured out oxygen’s role; and beyond!

Genres: Nonfiction, Teen

136 pages, Library Binding

Published August 4, 2026

Reviews

[YSBR]

Rather than presenting a dry biography of the British anatomist William Harvey, Maria Parrott-Ryan has instead placed her account of his paradigm-busting investigation of the circulatory system inside a history of the scientific revolution. While we don’t learn much about Harvey’s childhood or personal life in the 17th century (really, do we need to?), we do get a thorough and entertaining account of the resulting evolution in “natural philosophy” as his work shoved medical knowledge forward. Students will be amazed to read about Harvey’s early education as a physician at the University of Padua, in which future doctors were lucky to see even one dissection and the ancient Roman Galen’s prevailing humoral theory (that the human body is governed by 4 fluids) rested entirely on conjecture.  Harvey’s obsession with dissection, vivisection (of animals), and experimentation, all of which Parrott-Ryan recounts vividly, compassionately, and with a droll sense of humor, came as a total break from accepted wisdom. This concise account packs an impressive amount of material into its well-organized pages, covering the history of ancient medicine, the prevailing beliefs and conventions that impeded scientific progress, contemporary discoveries in the Islamic world, and a clear explanation of how the circulatory system functions. Well spaced lines of type, plentiful sidebars, and occassional background essays (for example, about the scientific revolution, the role of women in medicine, or attitudes toward vivisection and animal research) all combine to make An Astonishing Circle a highly readable book. Most striking, however, are the subtle parallels the author has drawn between Harvey's era and our own: the resilience of myth masquerading as fact, and the resistance faced by discoveries born of observation and experimentation. 

Despite its compact size (the ARC measuring just 5 by 8 inches), the book is remarkably attractive and visually appealing. The pages have facsimile foxing that suggest age and each page number appears on a splattered drop of blood. Frequent and fascinating primary source images will encourage readers to linger: a photo of Padua’s anatomical theater, period anatomical engravings (including an example from Vesalius in which a man made entirely of muscles cavorts in the countryside), and the regular appearance of maps, cartoons, portraits, and famous paintings of dissections. Recognizing that her readers may be learning about circulation for the first time, Parrott-Ryan has also thoughtfully included modern illustrations that diagram “Your Heart’s Parts”, pulmonary circulation, and the role of bone marrow in creating blood cells. A glossary, timeline, index and additional short paragraphs about women and people of color in medicine close out the book. Link to complete review: https://ysbookreviews.wordpress.com/2...

[Alicia]

What an intelligent story that mixes the gruesome with the academic. Parrott-Ryan introduces readers to the names of the time who had to push boundaries and test the limits of science with their experiments and thoughts-- some got people pushed out of the intellectual community or ran out of town because of their beliefs but it's how science was developed-- crazy ideas that ended up being not so crazy including how the heart worked in it's "astonishing circle". Some of these men (of course they were basically men as described by the historical context) waited YEARS to publish their findings because they feared the repercussions of their findings. But often times had no qualms about vivisection-- dissecting an animal that was still alive to see how things worked "in real time".

The illustrations and documentation makes my goth heart happy. It's mood is exactly the tone of the story.