Mulligan's poem in Telemachus strives to offend Catholic sensibilities twice in one line: "My mother's a jew, my father's a bird." Christians have long thought of Jesus and his blessed mother as something other than Jews, and when they put doves in Annunciation scenes they do not think of the Holy Spirit literally as a randy bird. The second joke returns in Proteus, with the dove demoted to a mere "pigeon," when Stephen recalls a work called "La Vie de Jésus by M. Léo Taxil."
In Nestor Mr. Deasy repeats the old canard that the Jews "sinned against the light," ignoring the fact that Jesus was a Jew. In Eumaeus Bloom recalls how he enraged the Citizen by saying "your God was a jew," reflecting that "mostly they appeared to imagine he came from Carrick-on-Shannon or somewhere about in the county Sligo." In the context of such ethnocentrism, Mulligan's "My mother's a jew," while factually unremarkable, is effectively insulting.
Saying "my father's a bird" goes further into the realm of blasphemy, by reading a traditional symbol of the Holy Spirit literally and imagining avian-human intercourse. The gospel of Luke recounts the angel Gabriel's visit to Mary in what became known as The Annunciation. The angel says that the Holy Spirit "will come upon you" (!), and that Mary will become pregnant with the Son of God. In later pictorial representations, the Holy Spirit often took the form of a dove. So, in Mulligan's mind, a testosterone-maddened pigeon came upon Mary and inseminated her.
The image fills Stephen's imagination as he walks toward "the Pigeonhouse" in Proteus. He recalls an exchange between Mary and her cuckolded husband Joseph, from La vie de Jésus (1884) by Léo Taxil (a pen named adopted by Gabriel Jogand-Pages). "Qui vous a mis dans cette fichue position?" demands Joseph ("Who has put you in this rotten position?"). Mary's desperate, but orthodox, reply: "C'est le pigeon, Joseph" ("It [was] the pigeon"). Gifford notes that this blasphemy angered the Vatican. Jogand-Pages was forced to apologize to the papal nuncio and to travel to Rome for "a well-publicized papal absolution" (53). In Oxen of the Sun, Stephen is still thinking of the passage: "parceque M. Léo Taxil nous a dit que qui l'avait mise dans cette fichue position c'était le sacré pigeon" (because M. Leo Taxil tells us that it was the sacred pigeon who put her in this rotten position), and the joke returns one more time in Circe.
The thought that a pigeon begat Jesus sends Stephen's mind on to a young man he knew in Paris named Patrice Egan. It was Patrice who recommended La vie de Jésus to Stephen. But Patrice has more than an incidental connection to the conceit. Since his father Kevin Egan is a "wild goose," he too can truthfully say, "My father's a bird." As in Stephen's conceit about algebra, where morris dances and Moorish turbans combine with the Moorish art of mathematics, the pieces interlock wonderfully.