ICHTHYS and acrostics: the fish as a profession of faith

An acrostic is a text in which the first letters of the lines, or of the words, spell out another word. The technique is extremely old. Some Hebrew psalms are already built on the order of the alphabet, such as Psalm 119, divided into twenty-two stanzas, one for each letter, and the book of Lamentations follows the same principle. The most famous acrostic in Christian history, however, is contained in a single Greek word: ICHTHYS, meaning “fish”.

Five words in one

The letters of ichthys are the initials of the formula Iesous Christos Theou Yios Soter, that is, “Jesus Christ, Son of God, Saviour”. The name of a common animal thus contained a short profession of faith. We do not know for certain whether the acrostic arose before the fish symbol or was discovered later, but between the second and third centuries the two elements already appear closely linked in Christian art and literature.

The symbol lent itself to several readings. It recalled the miraculous catch and the calling of the apostles to become fishers of men, the multiplication of the loaves and fishes, baptism in water. Tertullian, in his treatise On Baptism, writes: “nos pisciculi secundum ichthyn nostrum Iesum Christum in aqua nascimur”, that is, we little fishes are born in water after our fish, Jesus Christ. The image joined the play on letters to the rite that marked entry into the community.

The inscriptions of Abercius and Pectorius

Two Greek inscriptions show the symbol in use. The epitaph of Abercius, bishop of Hierapolis in Phrygia at the end of the second century, speaks allusively of a most pure fish, caught by a virgin, which faith offers as food to the faithful; an original fragment of the stone is kept in the Vatican Museums. The veiled language of the inscription was fully understandable only to those who knew Christian symbolism.

At Autun, in Gaul, the inscription of Pectorius, whose date is debated, was found in the nineteenth century, written in Greek verse. Its first lines form the acrostic ICHTHYS, and the text speaks of the “divine race of the heavenly fish” and of the honey-sweet food of the Saviour. It is one of the clearest witnesses to the fusion of acrostic, funerary poetry and sacramental language.

The Sibylline acrostic, Augustine and Boccaccio

The Sibylline Oracles, a collection of prophetic verses of Jewish and Christian origin, contain in their eighth book a long acrostic whose initials form the fish formula with the addition of stauros, “cross”. Augustine, in the eighteenth book of The City of God, gives a Latin translation of it and explains the game of initials to the reader, a sign that the text was regarded as precious evidence of pagan prophecy about Christ.

In the Middle Ages and the Renaissance the acrostic became a common ornament in dedicatory poems, where the initials of the lines spelled the name of the recipient or of the author. The most ambitious case in Italian literature is Giovanni Boccaccio's Amorosa visione: the initial letters of its tercets, read in sequence, form three complete sonnets, one of them dedicated to a woman loved by the poet.

The fish drawn on a tombstone, often reduced today to a simple outline, was therefore also born as a game of letters. Remembering this helps us understand how the first Christians experienced writing: a common noun could hold a declaration of faith, recognisable to those who knew the code. The same idea, that one text can conceal another, runs through the whole history of the acrostic, from the psalms to Italian poetry.