During the Middle Ages, Vitruvius’s de Architectura was forgotten and only rediscovered in 1414. Leonardo da Vinci’s predecessor and early Renaissance humanist, Poggio Bracciolini had included it in his collection of classical writing when he discovered it the Library at Abbey of Saint Gall in St. Gallens, Switzerland. 

The rest of his collection, which was curated from libraries all over Western Europe, include Astronomica, detailing astronomical phenomena, by Manilius, De Aquaeductu, or On Aqueducts, by Frontinus, and De Rerum Natura, or On the Nature of Things, by Lucretius.

This collection of classical writing largely influenced Renaissance thinking. Apart from de Architectura, the poem, On the Nature of Things, led to Renaissance philosophy and the knowledge-seeking ideal. The poem describes a multitude of phenomena, including that everything in the world is comprised of small particles, which we know of as atoms now.

Source: Isaacson, Walter. “Chapter 8 Vitruvian Man.” Leonardo Da Vinci: The Biography, Simon & Schuster, 2018.