On light.

That luminous body which is found to be enveloped by thicker air will appear of smaller size, as is shown in the moon or the sun when veiled by mist.

On light.

Among luminous bodies of equal size, distance and splendour, that one will appear of greater form which is surrounded by a darker field.

On light.

I find that every luminous body seen in dense and thick fog diminishes the more it moves away from the eye; and so does the sun by day, as do the moon and the other mortal lights by night. And when the air is pure, the more these lights move away from the eye, the more they seem to grow greater in form.

On the sea that girds the earth.

I find that in ancient times the site of the earth was, in its plains, wholly occupied and covered by the salt waters, and the mountains, the bones of the earth, with their broad bases penetrated and rose up into the air, covered and clothed with much high soil. Then the many rains, the swelling of the rivers, with frequent washings, have in part stripped bare the high summits of these mountains. Leaving the ground of the earth, the rock is found surrounded by the air, and the earth departed from those places, and already ... And the earth of the shores and of the high mountain summits has already descended to their bases and has raised the beds of the seas that those bases enclosed, making an uncovered plain; and thence, in some places, over a distant space, it has driven back the seas.