Leonardo da Vinci

Leonardo is the most radical pre-Baconian empiricist: "Wisdom is the daughter of experience." He rejected the authority of ancient texts in favour of direct observation — anatomy by dissection, mechanics by experiment, optics by drawing.

"Those who are enamoured of practice without science are like a pilot who goes into a ship without rudder or compass and never has any certainty of where he is going." (Codex Atlanticus)

Leonardo's world is entirely natural: every phenomenon — flight, flowing water, light, muscular motion — is governed by discoverable natural laws. He does not invoke supernatural causes in his scientific investigations.

"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." (Notebooks)

Despite the empiricist priority, Leonardo insists that mathematics is the key to understanding nature — "No human investigation can be called true science unless it passes through mathematical demonstrations."

"No human investigation can be called real science if it cannot be demonstrated mathematically." (Treatise on Painting)

Leonardo's conviction that painting is a "mental science" and the supreme form of knowledge — because it engages the eye, the noblest sense, and requires the artist to understand the laws of nature — is a foundational statement of the aesthetic-epistemic tradition.

"Painting is a cosa mentale — a mental activity — and the painter who merely copies nature without understanding it is like a mirror." (Treatise on Painting)

Leonardo's notebooks anticipate key features of the scientific method: hypothesis formation, systematic observation, experimental testing, and mathematical formalization — a century before Bacon's Novum Organum.

"Experience never errs; it is only your judgements that err by promising themselves effects such as are not caused by your experiments." (Codex Atlanticus)