The veins, vena, are so called because they are the channels, vie, of flowing blood and streams which are spread throughout the whole body, by which the members are supplied with blood. Blood, sanguis, gets its name from Greek etymology, because it is active, it survives and it has life. When it is in the body, it is called sanguis; when it pours forth, it is called gore, cruor. It is called cruor because when it is spilled, it runs down, decurrere; or because when it runs, it sinks into the ground, corruere. Others take cruor to mean corrupt blood which is discharged from the body. Others say blood is called sanguis because it is sweet, suavis. Except in young people, the blood supply does not remain constant. For physicians say that it diminishes with age, which is why old people have tremors. Strictly speaking, however, blood is a property of the soul. For this reason women tear their cheeks in grief, and we furnish the dead with purple clothing and purple flowers.
Isidore on the parts of man’s body. The lung, pulmo, gets its name from the Greek. The Greeks call the lung, pleumon, because it acts as a fan for the heart, in which the pneuma, that is, the spirit resides, by which they are both activated and set in motion; for this reason lungs too are called pulmones. In Greek the spirit is called pneuma; by inflating and activating, it sends out and takes in air, causing the lungs to move and throb, opening in order to catch a breath, contracting to expel it, for it is the organ of the body.
The liver, iecur gets its name because it is the seat of a fire which flies up to the brain. From there the fire is spread to the eyes and other senses and members of the body, and by its own heat, draws the moisture from food to itself and turns it into blood which supplies each part of the body with food and nourishment. Pleasure and lust reside in the liver, according to those who debate scientific matters. The extremities of the liver are filaments, fibre, like the outer parts of leaves on the vine or like projecting tongues. They are said to be so called because among pagans they were borne by soothsayers in religious rites to altars of Phoebus, so that when they had been offered up and burned, the soothsayers would receive answers.