The Manifesto
"La pittura è cosa mentale."
"Painting is a thing of the mind." — Codex UrbinasWith this single phrase, Leonardo repositioned painting from a manual craft (arte mechanica) to an intellectual pursuit on par with poetry and music. The painter wasn't a craftsman mixing pigments — he was a thinker decoding the visible world.
The Paragone: Painting's Supremacy
Leonardo's Paragone (comparison) arguments occupy the opening chapters of his Treatise on Painting. His case:
- Painting vs. Poetry: "Painting is poetry which is seen and not heard, and poetry is painting which is heard but not seen." The eye takes in a whole scene simultaneously; the ear processes poetry sequentially. Painting has immediacy.
- Painting vs. Sculpture: Painting can show atmospheric perspective, distant backgrounds, weather, and emotion through color — things sculpture cannot. He also jibed that sculpture "causes the artist's brow to sweat" while painting demands mental, not physical, exertion.
- Universality: "A painting of a story will be understood by all nations without words." Painting transcends language.
Moti Mentali — The Movements of the Mind
"The good painter has to paint two main things: the man and the intention of his mind. The first is easy, the second difficult, because it must be expressed through gestures and movements of the limbs."
Treatise on PaintingLeonardo's most original contribution: insisting that depicting the mind is the painter's higher challenge. He wrote that figures without appropriate gestures expressing their inner state are "twice dead" — lifeless as paint, and lifeless as character.
He cataloged the physical signs of emotion: how the brow furrows in anger, hands are thrown up in despair, the body recoils in fear. He suggested studying deaf people who use sign language because "they make gestures better than any other sort of men."
In Leonardo's Works
The Last Supper
Thirteen different emotional responses to "One of you shall betray me" — captured simultaneously. Thomas raises his finger in anxious demand. Philip presses his hands to his chest in sincere hurt. Peter grips a knife in rash anger. Judas recoils in guilt, clutching the money bag. John swoons in sorrow. No prior painting had achieved such psychological variety within a single narrative moment.
Mona Lisa
The triumph of cosa mentale. Her smile exists in the viewer's perception, not fixed on the panel. Harvard neuroscientist Margaret Livingstone (2003) demonstrated that sfumato around the mouth exploits the difference between foveal and peripheral vision — the smile appears when you look at the eyes, vanishes when you look at the mouth. Leonardo engineered an optical illusion that makes the painting interact with the viewer's brain.
St. John the Baptist
Deliberate perceptual ambiguity as artistic strategy. The figure emerges from total darkness with an enigmatic smile and a pointing finger — the gesture is clear (toward heaven) but the emotional tone is deliberately elusive. Sacred or secular? Solemn or playful? Leonardo forced the viewer to actively project meaning, creating a longer, more contemplative interaction with the image.
The Grotesque: Mapping the Limits of Expression
Leonardo's famous caricature drawings were not idle doodling — they were systematic studies of how much a face can be distorted while still communicating recognizable character. By exaggerating features (bulbous noses, jutting chins, collapsed mouths), he discovered that perception of temperament is triggered by a few key feature distortions. He was essentially mapping the limits of recognizable human expression — centuries before psychology or caricature became formal disciplines.