How did the expression “white bone and blue blood”?

people are rarely on the street, as usual, pale and delicate, pale skin, through which shines through the venous - arterial system, is visible to the system through the skin in blue color. Especially this appearance was evident in Sunny countries where only the rich, wealthy person could afford "not to bathe" in the sun, and to be thrilled in the cool of the building or shady garden, as a rule, the rich people were of noble birth. Bela bone is allegorical expression associated with white color combined with white color. poba these concepts blue blood and white bone is a symbol of noble, the origin of man.
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