Quotation from: The Notebooks of Leonardo Da Vinci

Written by: Leonardo da Vinci

It is of necessity that there should be more water than land, and
the visible portion of the sea does not show this; so that there
must be a great deal of water inside the earth, besides that which
rises into the lower air and which flows through rivers and springs.

[Footnote: The small sketch below on the left, is placed in the
original close to the text referring to the Dead Sea.]