Sky blue, the blues, the deep blue ocean, the blue devils.
The first time that a word for the color blue appears is about 4,500 years ago. Until that time there was, apparently, no word for blue. But to be fair, 4.500 years ago we were probably lacking words for lots of things.
One might safely presume that throughout human history the sky has always been blue (except at night or at sun rise or set and, of course when the sky is cloudy, but you know what I mean). This is because the wave length of blue is very short and scatters more readily in the mix that makes up the air of earth’s atmosphere than do the other colors in the spectrum.
Similarly, the world’s oceans (and our beloved lakes here in Minnesota) are blue because the non-blue colors are absorbed by the molecules that make up the waters they contain. Leaving the blue to seem to be the color of the water.
For centuries blue pigments were made from minerals such as lapis, which is a semiprecious stone mined almost exclusively in what is now Afghanistan. This was a very expensive pigment and at times its value rivaled that of gold. Because of its expense its use in classical art was saved for very special things such as the robes of the Virgin Mary.
Early blues also came from mineral mixes such as those developed by the ancient Egyptians to get what we now know as, wait for it, Egyptian Blue. Egyptian Blue resulted from a careful combining of limestone, sand and naturally occurring coppers which contained azurite or malachite. These were mixed and melted to form a glass frit which could then, in turn, be ground and mixed, as a pigment, with a variety of vehicles.
Another blue, indigo is not a pigment but is, rather, a die which is derived from a plant easily grown in many parts of the world. Indigo was used to color fabrics until it was supplanted by the the development of a synthetic colorant in 1880. (A supplanted plant.)
Prussian blue resulted first from a combination of cochineal reds and the red of animal blood. The chemical reaction of these ingredients created blue.
The blues (in both song and feeling) apparently gets its name from the term “the blue devils” which, in its turn is used to describe visual hallucinations which accompany the delirium tremens associated with alcohol withdrawal. History though seems quiet about why this unpleasantness was laid onto the shoulders of blue.
Personally one of my favorite applications of blue is the song “Blue” sung by the Jayhawks (a Minneapolis, Minnesota band) in 1995 on their album “Tomorrow the Green Grass.”