Quotation from: The Notebooks of Leonardo Da Vinci

Written by: Leonardo da Vinci

The summits of mountains for a long time rise constantly.

The opposite sides of the mountains always approach each other
below; the depths of the valleys which are above the sphere of the
waters are in the course of time constantly getting nearer to the
centre of the world.

In an equal period, the valleys sink much more than the mountains
rise.