Carlo Pedretti

The Scholar

Carlo Pedretti (1928–2018) was the most prolific Leonardo scholar of the twentieth century. Born in Bologna, he published his first scholarly paper on Leonardo at age nineteen and spent the next seventy years — literally until his death at age ninety — working on the notebooks. He held the Armand Hammer Chair in Leonardo Studies at UCLA for decades, building it into the world's leading center for Leonardo research.

Where Richter organized by subject and MacCurdy organized for accessibility, Pedretti asked a different question entirely: when was each page written? This seemingly simple question turned out to require forensic-level investigation — and its answers transformed Leonardo scholarship.

Pedretti's method was codicological: he studied the physical manuscripts themselves — paper types, watermarks, ink colors, handwriting evolution, physical damage patterns — to determine when and where Leonardo wrote each page. Combined with cross-referencing internal evidence (dates mentioned, events described, people named), Pedretti could often date pages to within a year, sometimes to a specific month.

The Problem Pedretti Solved

Before Pedretti, scholars treated Leonardo's notebooks as a flat landscape. A passage about water from Manuscript A sat beside a passage about water from the Codex Leicester as if they were written at the same time by the same mind in the same mood. They weren't. Manuscript A dates to the early 1490s; the Codex Leicester to around 1508. Between those dates, Leonardo had lived in Milan, fled to Venice, returned to Florence, served as Cesare Borgia's military engineer, and completely revised his understanding of fluid dynamics.

Pedretti showed that Leonardo's ideas evolved. His early anatomical observations are based on traditional authorities; his later ones are based on direct dissection. His early thoughts on painting are systematic and rules-based; his later ones are more fluid and atmospheric. His early mechanical designs are optimistic; his later ones are tempered by engineering reality. Without chronology, you can't see any of this.

The Forensic Toolkit

Pedretti used multiple independent lines of evidence to date Leonardo's pages:

The Commentary on Richter (1977)

Pedretti's most important single work for textual scholarship was his two-volume The Literary Works of Leonardo da Vinci: Commentary (1977), published by Phaidon. This monumental work took Richter's 1,566 passages one by one and updated them: correcting dates, identifying manuscript sources more precisely, noting where pages had been misattributed, and cross-referencing against discoveries made in the ninety years since Richter's first edition.

The genius of Pedretti's approach was structural: he kept Richter's numbering system intact. His Commentary is organized as annotations to Richter's passages, not as a replacement. This meant scholars could continue using Richter's universally known reference numbers while incorporating Pedretti's corrections — a brilliant act of scholarly diplomacy that ensured continuity.

Revealing the "False Codices"

One of Pedretti's most consequential findings was demonstrating that several of the most famous "notebooks" are not notebooks at all. They are modern compilations:

• Codex Atlanticus — assembled by Pompeo Leoni in the 1590s from cut-up pages spanning Leonardo's entire career. It's an anthology, not a notebook.
• Windsor Collection — Leoni grouped drawings by subject (anatomy, horses, landscapes), destroying their original manuscript context.
• Codex Arundel — a bound collection of loose sheets from multiple periods, probably assembled after Leonardo's death, possibly by Melzi.

Understanding this changes everything about how you read these collections. A "page" of the Codex Atlanticus might combine a fragment from 1490 with one from 1515, glued together by a man who thought subject-matter was more important than chronology. Pedretti peeled apart these layers.

Through decades of work, Pedretti established a detailed chronological framework for Leonardo's manuscript production. While individual datings remain debated, the broad structure is now accepted by the field:

What Pedretti Gets Right

• Intellectual biography — finally possible to trace how Leonardo's ideas developed over 40 years
• Manuscript integrity — identifying "false codices" restores the original notebook structures
• Cross-disciplinary connections — dating reveals that Leonardo's water studies and painting experiments happened simultaneously, suggesting causal links
• Scholarly continuity — preserving Richter's numbering while adding chronological data
• Physical evidence — grounding attributions in material science rather than stylistic opinion

What It Misses

• Subject access — if you just want Leonardo's thoughts on painting, chronological ordering scatters them across decades
• Certainty — many datings remain contested; Pedretti himself revised his own chronology multiple times
• Specialist density — his Commentary is written for experts, not general readers
• Publication complexity — his work is scattered across dozens of books, articles, and lectures over 60+ years, making it hard to find a single definitive statement on any topic

Legacy

Pedretti's influence on Leonardo scholarship is immeasurable. Before him, the notebooks were a reference library; after him, they became a biography. Every subsequent major work — Kemp's interpretive synthesis, Bambach's four-volume chronological study — builds on Pedretti's foundational dating work.

His students and protégés continue the chronological project. The Armand Hammer Center at UCLA that he built remains the institutional home of Leonardo manuscript studies. And his insistence on physical evidence — look at the paper, the watermarks, the ink — established a standard of rigor that moved Leonardo scholarship from connoisseurship to something approaching forensic science.