Leonardo & the Human Machine
Five centuries ago, a man with no formal medical training produced anatomical drawings so advanced that modern surgeons still reference them today.
“A beautiful body perishes, but a work of art dies not.”
— Leonardo da Vinci
Tucked into thousands of pages of his notebooks and buried in mirror-script, scattered across studies of flying machines and hydraulic systems — are some of the most precise, beautiful, and scientifically insightful anatomical drawings ever created.
This is the story of how one man, with nothing more than paper, ink, and first principles thinking, decoded the most complex machine in nature —
The human body
The Skull That Sparked a Scientific Awakening
In 1489, Leonardo da Vinci acquired a human skull — likely from a medical practitioner in Milan. Rather than study it from the outside, as was common at the time, he saw it as a puzzle to be deconstructed.
He cut it apart in sections and drew each view with painstaking accuracy: the sinus cavities, the jaw articulation, even the tiny foramina (holes through which blood vessels and nerves pass.)
Why such obsessive attention to detail? Leonardo believed that to understand The Whole, you had to break it down to its component parts.
This is the essence of First Principles Thinking and the Thinking Process.
The Spine is a Rhythm, not a Rod
Before Leonardo, most depictions of the human spine showed it as a straight pole — kind of like a staff running through the body. However, Leonardo’s observations of real human remains told a different story.
He noticed how the curvature of the spine, the tilt of the pelvis, the balance of vertebrae allowed humans to walk upright with grace and control.
In fact, he saw the skeletal as systems of levers and fulcrums, similar to architectural arches or mechanical load-bearing columns.
Three-Dimensional Vision
Leonardo’s approach was unique not only for its accuracy, but for his use of perspective.
He was arguably the first to create three-dimensional anatomical schematics — layered views that resemble modern engineering diagrams.
Prior to the Renaissance, most illustrations were flat and lacked dimensionality. Leonardo’s were spatial, immersive, and were constructed like blueprints to be studied.
Today, we teach medical students with cross-sectional models and 3D software.
Leonardo did it with chalk, ink, and observation.
No shortcuts.
Just raw observational insight and hard work.
A Peaceful Death Leads to a Cardiovascular Discovery
In the winter of 1507–08, Leonardo was at the Hospital of Santa Maria Nuova in Florence when an elderly man passed away peacefully in his sleep.
Curious about the calmness of the man’s death — what he described as a “sweet death” — Leonardo performed a post-mortem dissection.
During the examination, he discovered that the man’s coronary arteries had hardened and narrowed.
Today, we call this condition atherosclerosis.
Leonardo was the first to describe it.
At the time, no one knew what caused heart attacks or strokes. Yet through first-hand observation and logical reasoning, Leonardo identified one of the leading causes of cardiovascular disease — a feat modern doctors didn’t officially codify until centuries later.
Comparative Anatomy Before It Had a Name
“Nature is the source of all true knowledge. She has her own logic, her own laws, she has no effect without cause nor invention without necessity.”
— Leonardo da Vinci
Leonardo didn’t limit his studies to humans. He dissected cows, bears, birds, frogs — anything he could get his hands on.
This comparative approach allowed him to identify patterns across species.
He noticed the structural similarities in bones, muscle groups, and organ systems. But more importantly, he used these comparisons to ask deeper questions:
What is universal?
The Womb, Revealed
One of Leonardo’s most haunting and celebrated drawings is that of a fetus in the womb, which was created from a combination of direct dissection (of animal wombs) and inference.
It remains the first scientifically accurate image of fetal development.
The drawing includes detailed renderings of the uterus and placenta.
“The noblest pleasure is the joy of understanding.”
— Leonardo da Vinci
Heart Valves and a 21st-Century Surgeon
Leonardo’s study of the heart stands as one of his most technically remarkable achievements.
Though he didn’t grasp the full mechanics of blood circulation (that would come with William Harvey a century later), he correctly identified how the mitral and aortic valves directed blood flow.
In 2005, a British heart surgeon named Francis Wells used Leonardo’s drawings to guide a new technique for mitral valve repair.
The result?
Faster recovery times for patients with heart conditions.
Teeth, Tendons, and the Art of Functional Design
Leonardo was also the first to document the human dental formula — correctly identifying the number, shape, and function of incisors, canines, premolars, and molars.
He knew that function was related to form. Sharp teeth cut. Flat teeth grind.
This same mindset applies to anything, whether you're studying dentistry, designing user interfaces or drawing a picture...
Understand why each element exists.
Each part has its purpose, and each part’s purpose should be balanced with the whole’s purpose.
The Lost Textbook That Could Have Changed Medicine
Between 1510 and 1511, Leonardo collaborated with Marcantonio della Torre, a professor of anatomy at the University of Pavia.
During this period, Leonardo created over 240 detailed anatomical illustrations, most of which remained unpublished.
Together, they had planned to write a textbook that would have combined empirical observation and aesthetic clarity — something that would have radically transformed medical education in Europe.
Unfortunately, della Torre died of the plague, Leonardo’s notes were never compiled, and the textbook was never finished.
What could have changed medicine in the 16th century didn’t reach the public until the 20th.
The Human Body as a Masterwork of Engineering and Grace
Leonardo, by deconstructing the body into its functional parts, was able to see it as a unified system.
— interdependent, harmonious, and beautiful
For him, anatomy was a cosmology. The body revealed truths about structure, balance, and universal design.
Leonardo’s anatomical work endures because it was built on a foundation of First Principles Thinking:
Identify the Problem or Question
Break Down the Problem to Its Fundamental Elements
Analyze and Understand the Basic Elements
Rebuild from the Ground Up
Whether you’re designing a product, solving a health challenge, or writing code, the application and process remains the same.
Have you ever applied First Principles Thinking to solve a question or problem like Leonardo did? Share your story below 👇
Final Thoughts
Leonardo da Vinci didn’t set out to be remembered.
He set out to understand.
And in doing so, he left behind work that still teaches us how to think — not just about the body, but about anything we desire.
Leonardo dissected the body to uncover its structure — rhetoric is how we dissect thought.
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With gratitude,
M. R. Post, Classical Aegis
Creator, Beyond the Cosmic Veil
Excellent article. So much information. so well put forth!