Leonardo da Vinci

Early life and the limitations of the historical record

Leonardo was born April 15, 1452, in or near the village of Vinci in the Republic of Florence. He was the illegitimate son of Ser Piero da Vinci, a notary, and a peasant woman named Caterina. The illegitimacy meant he was not eligible for the standard Florentine notarial training his father's family practiced; this exclusion is sometimes cited as a structural factor in his subsequent decision to pursue painting and engineering rather than law.

Documentary records of his childhood are sparse. Unlike John Stuart Mill, whose father wrote extensively about his early education, or Mozart, whose father documented his musical training in correspondence, Leonardo's childhood is mostly inferred from later remarks by his biographer Giorgio Vasari (writing 60 years after Leonardo's death) and from a small number of surviving documents at the Vinci communal archive.

This documentary sparseness is the central methodological problem for any retrospective IQ estimate of Leonardo. Cox's 1926 method scored subjects partly on the precocity of their documented childhood accomplishments. A subject whose childhood went undocumented because of low literacy and social position - as was true for Leonardo and for many rural Italians of his century - looks, on the Cox metric, like a subject with low childhood precocity. This is a methodological artifact, not a measurement.

Apprenticeship and the workshop years

Around 1466, at age 14, Leonardo entered the Florentine workshop of Andrea del Verrocchio, one of the most distinguished artist-engineers of the period. The Verrocchio workshop trained painters, sculptors, and engineers together; it was the standard pathway for talented children of Florentine artisanal families. Leonardo remained there for roughly a decade as an apprentice and then as a workshop assistant.

His earliest documented painted work is the angel in Verrocchio's Baptism of Christ (c. 1472), where Leonardo executed the left-foreground angel's head. Vasari's biography includes a story - probably apocryphal but persistent in the literature - that Verrocchio gave up oil painting after seeing how much better Leonardo's angel was than his own figures in the same panel.

Leonardo registered with the Florentine painters' guild in 1472 at age 20. He continued working in Florence through the 1470s, taking on increasingly independent commissions including the unfinished Adoration of the Magi (1481, never completed because of his move to Milan).

Milan years and the major notebook period (1482-1499)

In 1482 Leonardo wrote a famous letter to Ludovico Sforza, the Duke of Milan, offering his services. The letter described his capabilities at length under ten engineering headings (mostly military: portable bridges, siege weapons, naval combat methods) before mentioning, almost as an afterthought, that he could also paint. Sforza hired him as a court engineer and artist.

The Milan years are the period in which Leonardo's notebooks become extensive. He kept working notebooks throughout his life but the surviving examples cluster around the 1482-1519 period. The notebooks include the famous anatomical drawings (over 240 surviving sheets), engineering studies (flying machines, portable cannons, hydraulic systems for the Sforza canal projects, designs for an ideal city after the Milan plague), and the artistic studies including the studies for The Last Supper (1495-1498).

The Last Supper was painted as a fresco-and-tempera mural in the refectory of Santa Maria delle Grazie. Leonardo's experimental painting technique - using oil-and-tempera over a dry wall surface rather than the traditional fresh-plaster fresco method - led to severe paint deterioration within his own lifetime. The painting has been repeatedly restored; what survives today is a substantial scholarly reconstruction rather than the original surface.

Anatomy and natural philosophy

Leonardo's anatomical work is among his most-studied contributions. Over the period 1487-1513 he dissected approximately 30 human corpses - against substantial cultural prohibition on the practice - and produced over 240 anatomical drawings that combine direct observation with a draftsman's ability to render three-dimensional structure intelligibly on a two-dimensional page.

The anatomical drawings include the first accurate representations of the cerebral ventricles (using a wax-injection technique he developed), detailed studies of the heart that anticipated the function of the aortic valves by approximately 450 years, and the first studies of fetal development based on direct dissection. The work was not published during Leonardo's lifetime and the notebooks were dispersed across European collections for centuries after his death.

His broader natural-philosophical work included extensive studies of water and turbulence, plant growth, geological observation (he correctly inferred from fossil evidence in Northern Italian rocks that the Po Valley had once been a marine environment - centuries before stratigraphy was established as a discipline), and the optics of light and shadow that he applied directly to his painting.

Late years, France, and the IQ-estimation problem

In 1517 Leonardo accepted an invitation from Francis I of France and moved to the Château du Clos Lucé in Amboise. He lived there with his student Francesco Melzi until his death on May 2, 1519. He left his notebooks to Melzi, who attempted to organize them but did not publish them; they were subsequently dispersed across European collections and have been partially reassembled over the following five centuries.

Cox's 1926 estimate of Leonardo's IQ at approximately 180 placed him in a middle range of her sample - well above the population mean but below figures like Goethe and Mill whose childhoods were better documented. Cox herself acknowledged the limitation: she wrote that subjects with poor childhood documentation were systematically underestimated by her method, and Leonardo was the most notable example in her sample of this kind.

Dean Simonton's 1976 study revisited the question with adult-achievement weighting. On Simonton's metric Leonardo's estimate rises substantially - placing him in the same range as Newton and Goethe. The Simonton revision is now generally taken to be more defensible than the original Cox figure, though both approaches share the underlying problem that they are not measurements, only retrospective inferences. There is no historical methodology that could produce a true IQ measurement for Leonardo da Vinci because no such instrument existed in his lifetime.

Timeline

• 1452Born in or near Vinci, Republic of Florence.
• 1466Apprenticed to Andrea del Verrocchio in Florence at age 14.
• 1472Registers with Florentine painters' guild at age 20.
• 1482Moves to Milan; offers engineering services to Ludovico Sforza in a famous letter.
• 1495Begins The Last Supper at Santa Maria delle Grazie.
• 1499Returns to Florence after the French invasion of Milan.
• 1503Begins the Mona Lisa.
• 1513Moves to Rome under the patronage of Giuliano de' Medici.
• 1517Moves to France at the invitation of Francis I.
• 1519Dies at the Château du Clos Lucé in Amboise at age 67.
• 1926Catharine Cox estimates his IQ at approximately 180 in The Early Mental Traits of Three Hundred Geniuses.
• 1976Dean Simonton revises the estimate upward based on adult-achievement weighting.

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