Why is the Sky and Sea Blue?

The whiteness or blackness of clouds come only from their exposure to the light of the stars, or to the shadow, both of themselves and of their neighbors.

There are only 2 things to note here.

1. The surfaces of transparent bodies reflect a part of the rays that come towards them.

This is why light can penetrate better through three pikes of water than it does through a little foam which is also water with several surfaces.

• The first surface reflects a part of this light
• The second surface reflects another part, and so on

In this way, almost none passes through.

This is why the following are not transparent:

• crushed glass
• snow
• thick clouds

2. The action of luminous bodies is only to push the fire-aether in a straight line to our eyes.

The ordinary movement of this fire-aether in the air is to roll.

This is like a ball rolling on the ground, even though it has only been pushed in a straight line.

The “white” bodies are those that can make them roll in this way. Examples of these are the bodies that lack transparency because of their many [layered] surfaces:

• foam
• crushed glass
• snow
• clouds

Why is the Sky and Sea Blue?

This is why the sky appears blue when very pure and free of all clouds.

The sky does not emit any light of its own.

It would appear extremely black if there were no exhalations or vapors at all above us.

Those exhalations or vapors always reflect some rays of fire-aether from the sun or stars towards our eyes.

When these vapors are in sufficient number, the fire-aether reflected towards us by the first vapors meets others.

• This collision makes its small parts roll and whirl before they reach us.
• This makes the sky appear white.

Whereas if it does not meet enough vapors to make its parts whirl in this way, it would only appear blue.

This is also why very pure and deep water is blue.

This is because:

• only a few rays are reflected from its surface
• none of those that penetrate it return*

Sunset and Sunrise

The sky towards the sun appears red when the sun sets or rises.

In those times, the light has to pass through:

• more clouds or fogs than during noon or daytime when the sky is blue
• less dark clouds as when the sky is gray

This light suffers refraction in these fogs.

It causes the fire-aether that transmit it to whirl in the same direction as a ball would that came from the same side rolling on the ground.

In this way, the whirling of the lowest ones is always increased by the action of those that are higher up, because it is supposed to be stronger than theirs.*

This is enough to make the red color appear, which is reflected afterwards in the clouds which spread them on all sides in the sky.

This color appearing in the morning presages winds or rain. This is because it shows that there are few clouds towards the East. It means that the sun will be able to raise a lot of vapors before noon. This will cause fogs to rise.

In the evening, this color testifies to good weather because there are only few or no clouds towards the west. This means that:

• the Eastern winds must reign
• the fogs descend during the night.