Twice in Proteus, Stephen thinks metaphorically of houses. Concluding his reverie about Richie Goulding's house in Irishtown, he thinks, "Houses of decay, mine, his and all. . . . Come out of them, Stephen. Beauty is not there." Later, he thinks of a saying about the medieval poet Guido Cavalcanti: "But the courtiers who mocked Guido in Or san Michele were in their own house. House of..." Both houses are "houses of decay." The artist is engaged in a war against entropy.
As first noticed by Edmund Epstein in "Cruxes in Ulysses: Notes Toward an Annotated Edition," The James Joyce Review 1 (1957): 25-36, the anecdote about "Guido" comes from a passage in Boccaccio's Decameron (6th day, 9th story) in which Guido Cavalcanti is brooding among the tombs around a church and some acquaintances mock him for his pensive solitude. Gifford quotes from the story: "Guido, you refuse to be of our society; but, when you have found out that there is no god, what good will it have done you?" Guido replies that they can say whatever they like to him, since they are in their own house. Thinking about his statement after he leaves, they realize that he means that their domain is Death: "these arches are the abode of the dead, and he calls them our house to show us that we . . . are, in comparison with him and other men of letters, worse than dead men."
Guido Cavalcanti (1250-1300) was a close friend and mentor of Dante Alighieri, and like him a troubadour poet who subjected love to rigorous logical analysis, seeking to understand its role in human life and the cosmos. Unlike Dante, he took little comfort in religious idealism, balancing a sense of love's spiritual exaltations with relentlessly scientific recognition of its limitations. Boccaccio's story of a somber contemplation of graves seems appropriate to this man who regularly looked emptiness in the face. Cavalcanti's reply to the courtiers (It is you who traffic in death, not I!) may express a belief that only those who are willing to examine their joys, and erect artistic structures to support them, can truly be said to live. Casual affirmation of life is really an acquiescence in our universal fate: death and decay.
Thinking of how poor a figure he cuts beside Mulligan's aquatic heroism, Stephen mentally rehearses Boccaccio's story to justify himself, but decides that it will not help him out of his embarrassment: "House of... We don't want any of your medieval abstrusiosities. Would you do what he did?" The earlier passage, however ("Houses of decay . . . Come out of them, Stephen. Beauty is not there"), shows him pondering the Cavalcanti saying in a more useful way. In A Portrait of the Artist as a Young Man, Stephen had argued that "When the soul of a man is born in this country there are nets flung at it to hold it back from flight. You talk to me of nationality, language, religion. I shall try to fly by those nets." Now, befitting the Protean theme, he thinks that to incarnate beauty he must extricate himself from the pockets of decay that would entrap him, and build his own house.