Ruefully setting off on Deasy's cattle disease business, Stephen thinks that Mulligan will now have yet another mocking nickname for him: "the bullockbefriending bard." But of course it is Stephen who is coining the phrase, and it coheres with other features of his persona, including the mythological associations of his last name, his tastes in philosophy and literature, and, most directly, his connections with his creator.
Before Dedalus crafted the wings to liberate himself and his son from Crete, he created an artificial cow inside which Pasiphae could satisfy her lust for a prize bull—an adventure which Stephen thinks about in Circe. In A Portrait of the Artist, he is associated with cattle in the opening section (a children's story about a "moocow") and much later when some fellow students call him "Bous."
In addition to these connections within the Joycean textual corpus, Gifford suggests allusions to two important figures in Stephen's intertextual cosmos: Homer and Thomas Aquinas. Homer, he argues, "befriended" the cattle of the god Helios by condemning the members of Odysseus' crew who slaughtered the god's cattle—and he was certainly a "bard." Aquinas was called "the dumb ox" by his fellow students at Köln. Gifford quotes a remark attributed to his teacher, Albertus Magnus: "We call him the dumb ox, but he will one day give such a bellow as shall be heard from one end of the world to the other."
But the immediate significance of the phrase lies in Stephen's agreement to deliver Mr. Deasy's letter to two newspaper editors, and in this he is much like James Joyce, who sufficiently sympathized with an acquaintance's concern about foot and mouth disease to write a letter to the editor of an Irish newspaper on the subject.