The decapitation of Saint John the Baptist. Stipple engraving by W.H. Egleton, 1844, after G.F. Barbieri, il Guercino.

Saint John the Baptist was the son of Saint Elizabeth, a relative (Greek "syngenis") of the Virgin. He was therefore a relative of Jesus Christ. His father was Zacharias. He is often depicted wearing camel's hair; with a lamb, referring to his description of Christ as the "Lamb of God"; with a cross of reeds held sometimes by him and sometimes by the lamb; and pointing with his index finger, to indicate his role as annunciator of Christ. His martyrdom by decapitation led to his being invoked especially against diseases associated with the head, such as migraine, epilepsy ("le mal Saint-Jean") and quinsy