Joyce's first allusion to Dante comprises a brief mention in a summary of Stephen's childhood education in Chapter 2, Part 4:
The memory of his childhood suddenly grew dim. He tried to call forth some of its vivid moments but could not. He recalled only names. Dante, Parnell, Clane, Clongowes. A little boy had been taught geography by an old woman who kept two brushes in her wardrobe.
Here, Stephen drowns out his father's sentimental stories with thoughts of his own childhood. The narrator refers to him as "a little boy" as if to distance the present Stephen from his past self. Dante is one of many names he recalls in a list of literary and historical figures that he learned about in his youth. Another significant allusion to Dante appears in Chapter 5, Part 4:
Met her today point blank in Grafton Street. The crowd brought us together. [...] She asked me why I never came, said she had heard all sorts of stories about me. This was only to gain time. Asked me, was I writing poems? About whom? I asked her. This confused her more and I felt sorry and mean. Turned off that valve at once and opened the spiritual-heroic refrigerating apparatus, invented and patented in all countries by Dante Alighieri.
In this scene, Stephen meets Emma Cleary at Grafton Street. Rather than addressing their personal history, he "turned off that [emotional] valve" and instead makes a joke about Dante, who obviously did not patent a "spiritual-heroic refrigerating apparatus." In fact, Dante most famously wrote about a journey through eight circles of hell in Inferno. This line might be a joke about the clash between nostalgia for old-world achievements (like Dante's epic poetry) and the rapid modernization of the early 20th century (including the development of in-home refrigeration). The joke, however, is somewhat hard to decipher, though what's most important to recognize is that Stephen uses humor and intellectualism to distance himself from emotional issues. To illustrate this, Joyce often alludes to major poets like Dante and Ovid in order to draw upon the authority of his predecessors.
The most important allusion in A Portrait of the Artist as a Young Man is, of course, to the Greek myth of Daedalus. Joyce named Stephen Dedalus after the mythical inventor Daedalus who creates wings made of feathers and wax to escape from Crete where he and Icarus (his son) are held captive by King Minos. Despite his triumphant artistry, the story has a tragic ending. Icarus ignores his father and flies too close to the sun, causing his wings to melt. He falls into the sea and dies.
In Chapter 4, Part 3, Stephen implicitly compares a flying form in the sky to an artist, which is a subtle allusion to the story of Daedalus and Icarus:
Was [the flying form] a symbol of the artist forging anew in his workshop out of the sluggish matter of the earth a new soaring impalpable being? … His soul was soaring in an air beyond the world and the body he knew was purified in a breath and delivered of incertitude and made radiant and commingled with the element of the spirit.
Here, Stephen's disdain for Dublin becomes clear. He derides the "sluggish matter" of the city and lauds Daedalus' ability to craft wings that allow him to escape. Stephen yearns for escape, and the sight of this flying form causes his soul to take flight. He is momentarily relieved of his former "incertitude," or uncertainty. Just as Daedalus created wings in his workshop, Stephen strives to forge definitions of art and beauty that will take him beyond the confines of his home. The original myth has a tragic ending, but the ending of Portrait implies that Stephen will continue to advance as an artist.
Thomas Aquinas was an Italian Dominican friar, theologian, and philosopher who is most famous for writing five key arguments in favor of God's existence. In Chapter 5, Part 1, Stephen quotes St. Thomas Aquinas:
— What the beautiful is is another question. —
He [the dean] rubbed his hands [...] — Can you solve that question now? — he asked.
— Aquinas — answered Stephen — says pulcra sunt quce visa placent.
— This fire before us [...] will be pleasing to the eye. Will it therefore be beautiful? —
— In so far as it is apprehended by the sight [...] it will be beautiful. But Aquinas also says Bonum est in quod tendit appetitus. In so far as it satisfies the animal craving for warmth fire is a good.
Aquinas's major works focus on the existence of God. However, Stephen chooses lines about art, beauty, and animal craving. The first Latin phrase translates to "the beautiful is that which pleases one's sight," and the second one translates to "the good is that which our instincts crave." Stephen quotes Aquinas (a prominent religious figure) in order to appeal to the dean and to advance his point about artistry. Both assertions seem to clash with the austere lifestyle required by the Jesuit college, but since they originate from an esteemed source, Stephen hopes to convince the dean of his points as he becomes increasingly enamored by the goodness of art and makes it—not religion—his most prized pursuit.
Joyce's work contains many allusions. For instance, Ovid's Metamorphoses appears twice in the novel. Metamorphoses is a narrative poem in 15 books written in Latin in the year 8 CE, and it chronicles the history of the world from its creation to the deification of Julius Caesar. The poem's epic mythical-historical framework lends credence to Joyce's novel as a worthy epic in its own right. The epigraph of Chapter 1 comes from its eighth book:
“Et ignotas animum dimittit in artes.” (OVID, Metamorphoses, VIII., 18).
This quote translates to, "And he sets his mind to work upon unknown arts." It is highly relevant to the first chapter, which describes Stephen as a child to whom higher arts are "unknown" (even though he finds great joy in the musical tolling of the chapel bell). In Chapter 5, Part 1, another allusion to Ovid appears:
One of the first examples that he had learnt in Latin had run: India mittit ebur; and he recalled the shrewd northern face of the rector who had taught him to construe the Metamorphoses of Ovid in a courtly English, made whimsical by the mention of porkers and potshreds and chines of bacon.
Here, Stephen recalls reading Ovid with a "shrewd Northern" rector who taught a courtly English translation of the original Latin. This moment stands in contrast to the first chapter; Stephen now has the capacity to reflect on his education and life experiences. The title "Metamorphoses" literally means "the changes"; here, Joyce uses the work to create symbolic resonance within the text and remind the reader of the changes that Stephen himself has undergone.
In A Portrait of the Artist as a Young Man, birds are often associated with changes, journeys, or gods. This motif also reminds the reader of Stephen's lofty aspirations. In Chapter 5, Part 3, Stephen observes a flock of birds:
They came back with shrill cries over the jutting shoulder of the house, flying darkly against the fading air. What birds were they? He thought that they must be swallows who had come back from the south. Then he was to go away? For they were birds ever going and coming, building ever an unlasting home under the eaves of men’s houses and ever leaving the homes they had built to wander.
Their "unlasting home" clashes with Stephen's wish to create something everlasting. He does not simply want to "come and go" like a bird; he desires artistic immortality. However, Stephen does resemble a bird in that he also desires freedom. Thus, this motif serves to support a range of themes including evanescence, freedom, and loftiness. It also subtly alludes to the myth of Icarus, who flies on feathered wings before plunging to his death into the sea. In the ancient world, some people believed in augury (divination by the flight patterns of birds). Stephen implicitly references this practice when he searches for meaning in his observation of birds.