Nobility - "Blue" Blood

"Blue" Blood

Blue blood is an English idiom recorded since 1834 for noble birth or descent; it is also known as a translation of the Spanish phrase sangre azul, which described the Spanish royal family and other high nobility who claimed to be of Visigothic descent, in contrast to the Moors.

The idiom originates from ancient and medieval societies of Europe and distinguishes an upper class (whose superficial veins appeared blue through their untanned skin) from a working class of the time. The latter consisted mainly of agricultural peasants who spent most of their time working outdoors and thus had tanned skin, through which superficial veins appear less prominently.

Robert Lacey explains the genesis of the blue blood concept:

It was the Spaniards who gave the world the notion that an aristocrat's blood is not red but blue. The Spanish nobility started taking shape around the ninth century in classic military fashion, occupying land as warriors on horseback. They were to continue the process for more than five hundred years, clawing back sections of the peninsula from its Moorish occupiers, and a nobleman demonstrated his pedigree by holding up his sword arm to display the filigree of blue-blooded veins beneath his pale skin—proof that his birth had not been contaminated by the dark-skinned enemy.