Percussion: the strongest of the four powers

Ms. A 8r

Leonardo became interested in the "four powers" of movement, weight, force, and percussion. Of these he considered percussion to be the strongest. Here he systematically studies the blow of an object (a ball) against a surface such as a wall, a bell, or another ball. He notes that the angle of incidence equals the angle of reflection. Leonardo's ideas about the physical laws of nature extended to his work as an artist. You can see this most of all in the Deluge drawings (at Windsor Castle; see below), leading to cataclysmic destruction. Percussion, he wrote, exceeds any other natural power (Codex Atlanticus 11vb). 

W912380. Source: https://www.royalcollection.org.uk/collection/

This is one of Leonardo's amazing drawings of the deluge. This image, like the others in the series, shows a cataclysmic storm overwhelming a landscape. His writing, near the top of the drawing, says "Of rain. You will show the degrees of falling rain at various distances and of varying degrees of obscurity, and let the darkest part be closest to the middle of its thickness." Here in the midst of this powerful, mysterious, emotionally-laden work of art he leaves this note reflecting his dispassionate, scientific approach. If someone asked him about this work he'd likely explain that he is maximizing the display of the force of percussion.