"A Treatise on Painting" by Leonardo da Vinci is a collection of writings begun in Milan between 1482 and 1499. Gathered from Leonardo's notebooks by his heir Francesco Melzi, this work argues that painting is a science. Through keen observations on expression, character, and natural phenomena, Leonardo examines the principles underlying artistic practice. First published in abridged form in 1651, the treatise was rediscovered and released in its complete modern form in 1817, preserving Leonardo's insights for future generations.