This morning I received a letter from . He writes that he does not believe scientific research into the nature of color and light can help the artist, neither can anatomy nor the laws of optics. He wants to discuss these questions with me and find out my views. Now everything depends on how this knowledge is to be used. But surely it is clear that we could not pursue our studies of light with much assurance if we did not have as a guide the discoveries of Chevreul and other scientists. I would not have distinguished between local color and light if science had not given us the hint; the same holds true for complementary colors, contrasting colors, etc. 'Yes', he will tell me: 'but these have always been taken into account, look at Monet' It is at this point that the question becomes serious!

Leonardo had also been wrestling with the question of why the sky appears blue, and around that time he had correctly concluded that it had to do with the water vapor in the air. In the Saint Anne painting, he portrays the sky’s luminous and misty gradations of blue as no other painter had done. The recent cleaning of the painting fully reveals the magical realism, veiled in vapors, of his distant mountains and skyline.

Outside is pure energy and colorless substance. All of the rest happens through the mechanism of our senses. Our eyes see just a small fraction of the light in the world. It is a trick to make a colored world, which does not exist outside of human beings.

If a little kid ever asks you just why the sky is blue, you look him or her right in the eye and say, "It's because of quantum effects involving Rayleigh scattering combined with a lack of violet photon receptors in our retinae."

When I set a glass prism on a windowsill and allow the sun to flood through it, a spectrum of colors dances on the floor. What we call "white" is a rainbow of colored rays packed into a small space. The prism sets them free. Love is the white light of emotion.

The world is blue at its edges and in its depths. This blue is the light that got lost. Light at the blue end of the spectrum does not travel the whole distance from the sun to us. It disperses among the molecules of the air, it scatters in water. Water is colorless, shallow water appears to be the color of whatever lies underneath it, but deep water is full of this scattered light, the purer the water the deeper the blue. The sky is blue for the same reason, but the blue at the horizon, the blue of land that seems to be dissolving into the sky, is a deeper, dreamier, melancholy blue, the blue at the farthest reaches of the places where you see for miles, the blue of distance. This light that does not touch us, does not travel the whole distance, the light that gets lost, gives us the beauty of the world, so much of which is in the color blue.

For many years, I have been moved by the blue at the far edge of what can be seen, that color of horizons, of remote mountain ranges, of anything far away. The color of that distance is the color of an emotion, the color of solitude and of desire, the color of there seen from here, the color of where you are not. And the color of where you can never go. For the blue is not in the place those miles away at the horizon, but in the atmospheric distance between you and the mountains.

atoms in the air scatter light from the sun and make the sky blue

Colors are the deeds/ and sufferings of light.

Science is not only a disciple of reason but, also, one of romance and passion.

This blue is the light that got lost. Light at the blue end of the spectrum does not travel the whole distance from the sun to us. It disperses among the molecules of the air, it scatters in water. Water is colorless, shallow water appears to be the color of whatever lies underneath it, but deep water is full of this scattered light, the purer the water the deeper the blue. The sky is blue for the same reason, but the blue at the horizon, the blue of land that seems to be dissolving into the sky, is a deeper, dreamier, melancholy blue, the blue at the farthest reaches of the places where you see for miles, the blue of distance. This light that does not touch us, does not travel the whole distance, the light that gets lost, gives us the beauty of the world, so much of which is in the color blue.

The scientist does not study nature because it is useful to do so. He studies it because he takes pleasure in it, and he takes pleasure in it because it is beautiful. If nature were not beautiful it would not be worth knowing, and life would not be worth living. I am not speaking, of course, of the beauty which strikes the senses, of the beauty of qualities and appearances. I am far from despising this, but it has nothing to do with science. What I mean is that more intimate beauty which comes from the harmonious order of its parts, and which a pure intelligence can grasp.

We have seven colours — violet, indigo, blue, green, yellow, orange and red (Roy G. Biv). Our atmosphere has a number of particles and when light falls on them, it gets scattered. With blue colour having less wavelength and more scattering qualities, it scatters and makes the sky blue. While red colour has opposite qualities than blue so traffic lights are of this colour.

Poets say science takes away from the beauty of the stars - mere globs of gas atoms. I, too, can see the stars on a desert night, and feel them. But do I see less or more?

Light is something like raindrops — each little lump of light is called a photon — and if the light is all one color, all the "raindrops" are the same.