Meaning of Blue
Symbolism and meaning of color is a very wide category of which numerous interpretations exist. However, throughout my research, the most relevant comments in my opinion are that blue stands for the vertical and the spatial, in other words height and depth, or the blue sky above, the blue sea below. It symbolizes that Masonry is as wide as these dimensions. It is also interesting to note that blue is considered to be "between black and white", also commonly identified with two opposing forces, good (white) and evil (black). Thus blue is considered the most neutral of all the colors. As Masons we are equal in our position with other members, regardless of color, rank, title or any other status, and it is very appropriate that blue would represent this equality. We can also say that this world is the neutral area, and we seek a deeper world, for the higher you go to heaven, the darker the blue sky becomes. In the same way, the deeper you go in the blue ocean, the darker it becomes.
It is also commonly used to represent religious feeling, devotion and innocence. Blue was one of the primary colors used to adorn the Tabernacle (see Exodus 26:1). To the Egyptians, blue was used to represent truth. The Egyptians had two theories about the creation of the world; one, that is was created by Thaut, who when he uttered any word caused the object to exist, and two, that it was the work of Ptah, The Great Artificer. Ptah's father was called Kneph, (also Cneph or Nef), and while many of the Egyptian Gods were adorned with different colors, Kneph is always depicted in blue. Kneph journeyed to the lower hemisphere, which appears to symbolize the evolutions of substances which are born to die and to be reborn. Isn't this similar to our belief in the immortality of the soul?
Blue is also considered the color for the spirit and the intellect. Jesus teaches in a blue garment, and the Virgin Mary is usually depicted in a blue mantle, as is the Norse god Odin. Vishnu of ancient Indian mythology is blue, and one of his incarnations, Rama, is blue-skinned, symbolizing his vastness as deep as the heavens. In Europe, the Blue Flower was the symbol of the greatest aspiration of the spirit.
In French, the word "bleu" is used as a substitute for the word "Dieu", which means God, as swearing was punishable in the middle ages by death. As such swear words such as "morbleu", "sacrebleu" and "parbleu" became popular substitutes in those times. The French royal family was associated with the color blue, because blue was associated with a celestial origin, and the royal family, like many royal families, also claimed to stem from this origin. As such the royal family was referred to as "de sang bleu" or godly blood. Even today, a substitute expression for aristocracy is "blue blood".