William Harvey — "I have not only affirmed, but also demonstrated, that the motion of the heart is…"
I have not only affirmed, but also demonstrated, that the motion of the heart is a perpetual circulation of the blood.
Get This Quote & Author's Image Illustrated On:
Click any product to generate a realistic preview. Up to 3 at a time.
* Initial load can take up to 90 seconds — revising the preview in another color is nearly instant.
Kitchen
Apparel
Other
More from William Harvey
"The physician must be a man of integrity and honesty."
"I have seen, and by my own experiments, demonstrated the truth of what I assert."
"It is by experiment alone that we can arrive at the knowledge of nature."
"The wise man will not be content with the knowledge of things as they are, but will seek to know how they came to be so."
"Nature is nowhere accustomed more openly to display her secret mysteries than in cases where she shows tracings of her workings apart from the beaten paths; nor is there any better way to advance the …"
About William Harvey (1578-1657)
English physician whose On the Motion of the Heart and Blood in Animals (1628) demonstrated blood circulation, overturning 1,400 years of Galenic medicine. Closely associated with Francis Bacon (his contemporary in the new English empiricism). For an intellectual contrast, see Galenic medicine, the 2nd-century Greek medical tradition (humors, blood-as-consumed-fuel) — Harvey calculated that the heart pumps more blood per hour than the body could possibly produce as fuel — a single quantitative observation that demolished the entire Galenic-Aristotelian medical worldview. The cleanest example in medical history of arithmetic disproving 14 centuries of authority.
Verification
Unverifiable
Found in 1 providers: grok
1 source checked
Understanding this quote
What it means
Harvey is asserting that he didn't merely claim the heart circulates blood continuously throughout the body — he proved it through systematic observation and experiment. The blood moves in a closed loop, pumped by the heart, rather than being consumed by tissues as previously believed. This distinction between assertion and demonstration was central to his scientific identity and methodology.
Relevance to William Harvey
Harvey spent decades dissecting animals, timing heartbeats, and calculating blood volumes to prove circulation experimentally. His 1628 work De Motu Cordis was the culmination of that rigor. As a physician to King James I and Charles I, and a fellow of the College of Physicians, he staked his professional reputation on empirical proof over inherited authority.
The era
In early modern Europe, Galenic medicine still dominated — blood was thought to be continuously produced in the liver and consumed by organs. Harvey's era saw the Scientific Revolution challenging ancient authority through observation. Vesalius had already corrected anatomical errors, but Harvey went further, using quantitative reasoning to overturn a 1,400-year-old physiological doctrine with measurable, repeatable evidence.
AI-generated insights based on extensive research and information for context. Factual errors? Email [email protected].