Monogram for the Holy Name
According to the ancient mind, a person’s name was the expression of his nature, work, or mission. Early Christians accordingly used our Saviour’s Name to bring to mind His adorable Person; and in their art they gave it the following shortened or symbolic forms:
c) Ichthys. The early Church loved another monogram for our Saviour’s name, the widely-used ICHTHYS. Christ’s full title was (in Greek): Iesous Christos Theou Yos Soter, Jesus Christ, Son of God, Saviour. The initial letters of these five words form the Greek word ICHTHYS, which means fish. For this reason Christ is often pictured as a fish. Thus both the abbreviation and the picture became for the early Christians a secret symbol for the Redeemer. Yes, they even call our Lord “the great and pure Fish” (Aberkios tomb inscription, about 180). Tertullian presupposed popular familiarity with the fish symbol when he wrote about 200: “We (Christians) are born as little fishes in water after the model of our Ichthys Jesus Christ” (On Baptism, ch. 1).