Friction is universally present in the motion of bodies in contact. The modern science of tribology seeks to explain the atomic details of friction; but the universality of friction may also be understood from a different perspective. Leonardo da Vinci, among his many investigations, studied the relationship between friction and the music of the heavens. He knew the music to be produced by the bumping and rubbing of the heavenly spheres and was concerned with the possibility of friction between these heavenly bodies:

“Had however this friction really existed, in the many centuries that these heavens have revolved they would have been consumed by their own immense speed of every day … we arrive therefore at the conclusion that the friction would have rubbed away the boundaries of each heaven, and in proportion as its movement is swifter towards the centre than toward the poles it would be more consumed in the centre than at the poles, and then there would not be friction any more, and the sound would cease, and the dancers would stop …” Leonardo da Vinci (1452-1519), The Notebooks, F 56 V

The music of the heavens being eternal, Leonardo understood that friction is absent from the state of grace. Thus confined to this mortal world, friction is a consequence of original sin.