Quotation from: The Notebooks of Leonardo Da Vinci

Written by: Leonardo da Vinci

75.

If the judgment of the eye is situated within it, the straight lines
of the images are refracted on its surface because they pass through
the rarer to the denser medium. If, when you are under water, you
look at objects in the air you will see them out of their true
place; and the same with objects under water seen from the air.