Anatomy and Proportion

The study of anatomy during the Renaissance was fraught with religious controversy. The Church generally frowned upon the dissection of human bodies, viewing it as a desecration of the sacred human form.

This prohibition greatly hampered knowledge of anatomy during this time, and acquiring cadavers for research was a taboo often navigated by robbing graves illegally.

So why did da Vinci persevere?

Leonardo’s insatiable curiosity in this area was rooted in his belief in the interconnectedness of art and nature. He saw the human body as a masterpiece of nature's design, a perfect blend of form and function, and sought to understand it in its entirety.

This fascination is visible in the intricate sketches of the human skull that he began drawing in 1489. The skull was one of his very first dissections.

In these early anatomical manuscripts, he depicted the cranium divided into two sections: one showing the exterior with teeth and jaw and the other showing the cavities within them.

Leonardo's anatomical sketches are celebrated for their precision and attention to detail. They also often went beyond static depictions of the human body and often constituted studies of the body in motion.

This reflected da Vinci’s fascination with the unity of form and function.

In his sketches, Leonardo meticulously displayed the interplay of veins, arteries, muscles, internal organs, and bones. He typically portrayed the body’s intricacies through transparent layers, which afforded an “insight” into the organ through the use of sections in perspective.

Even though his medical investigations remained private and went unpublished during his lifetime, the wealth of Leonardo’s drawings that have survived forged are still considered exemplars of scientific illustration.

Leonardo's detailed studies of the human skeleton, muscles, and internal organs garnered a great deal of valuable insights into the human body. His clever scientific illustration techniques - such as his use of cross-sections, transparent overlays, and perspective - have also stood the test of time.

In terms of medical progress, Leonardo was one of the first people to accurately represent the human spine in all its complexity.

Additionally, Leonardo's studies of the heart were so advanced that they prefigured modern cardiology.

His understanding of the heart's structure and function, as depicted in his sketches, was far ahead of his time. For example, he was aware of the four chambers of the heart, the existence of heart valves, and the important idea of coronary circulation.

One of Leonardo's most famous anatomical works is titled 'Studies of the Fetus in the Womb'. These two colored and annotated sketches were made around 1511 and provide a staggeringly detailed depiction of a fetus in utero.

These sketches showcase Leonardo's innovative use of cross-sections and multiple perspectives - techniques he used to represent the complex structure of the dissected womb and the correctly positioned fetus within it.

Leonardo accurately depicted the uterus as having a single chamber. This was in contrast to the prevailing belief that it had multiple chambers that divided fetuses into separate compartments in the case of twins!

Leonardo's anatomical studies enabled him to depict the human form with unparalleled realism and accuracy. His enriched understanding of both the structure and function of the human body, allowed him to confidently portray human figures in an array of expressive poses and actions, capturing the subtleties of movement and posture.

His understanding of facial muscles and their connections also made da Vinci skilled in conveying emotions, making ready use of the play of light and shadow over muscles, and bones.

Combined with his skilled representation of the texture and surface of the skin, this anatomical realism adds beautiful depth to the faces in da Vinci’s paintings.

The study of human proportion wasn’t a new concept. The ancient Greeks and Romans also studied the human form in great detail, producing some of the most accurate sculptures that remain to this day.

However, during the Renaissance, these studies took on a new lease of life, as the human form was believed to reflect the divine perfection of the universe, as created by God.

Prominent artists such as Albrecht Dürer conducted extensive studies on human proportions, aiming to discover a mathematical and aesthetic ideal.

By far the most famous product of the study of human proportion during the Renaissance is the 'Vitruvian Man', a drawing by Leonardo.

It’s a work that is widely considered to be among the all-time most iconic images in Western civilization.

It’s dated to around 1490 and depicts a nude man in two superimposed positions with his arms and legs apart, inscribed in a circle and square. It is an attempt to represent the mathematical principles that govern the proportions of the human body.

The drawing of the 'Vitruvian Man' was named after the ancient Roman architect Vitruvius, who lived during the 1st century BC. Vitruvius is best known for his multi-volume treatise titled De Architectura.

This treatise, which is the only treatise on architecture to have survived from antiquity, outlined his principles governing Greek and Roman buildings, as well as the ideal proportions of the human body.

Little is known with certainty about Vitruvius’ life, but his discussion of perfect proportion in architecture and the human body directly inspired Leonardo’s sketch.

Leonardo was a great admirer of Vitruvius, and he sought to visually represent the architect's concept of the proportionally ideal human body in his drawing.

The Vitruvian Man is known for exhibiting what’s known as the 'golden ratio' in the man's height relative to the distance between his navel and foot.

The 'golden ratio' - also known as the divine proportion - has been a phenomenon of interest since ancient times due to its unique mathematical properties and its aesthetic appeal.

Often denoted by the Greek letter phi (Φ or φ), it is approximately equal to 1.618. This means that if you have a line that's 1.618 units long (let's say meters for simplicity), and you divide it so that the longer segment is 1 meter and the shorter segment is 61.8 centimeters, you've divided it according to the golden ratio.

While Leonardo did not explicitly discuss the golden ratio (as far as current evidence suggests), many scholars and enthusiasts believe that he was aware of it and applied it in his works, which would align with his deep interest in the mathematical principles that govern the proportions of the human body.

The golden ratio is related to the 'Fibonacci sequence': a series of numbers in which each number is the sum of the two preceding ones, usually starting with 0 and 1. So, the sequence goes 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, and so on.

When you take the ratio of successive Fibonacci numbers, you'll notice an interesting phenomenon.

As you move further along the sequence, the ratio of one number to its preceding number gets closer and closer to the golden ratio. For example: 5/3 = 1.666... 8/5 = 1.60... 21/13 = 1.615... 34/21 = 1.619... The golden ratio and Fibonacci sequence can be found almost everywhere in nature, as well as in the proportions of the human body, and many great works of art and architecture.

A commonly cited example is the nautilus shell, which grows in a logarithmic spiral. If you measure the various dimensions of its coil and their ratio from one chamber to the next, they often approximate the golden ratio.