Instead of thinking of the massive stones of the Great South Wall as the work of 18th century engineers, Stephen weaves a fanciful picture of "Sir Lout" and other prehistoric giants, drawing together strands from Irish mythology, children's rhymes, and his own fertile imagination.
Frank Budgen recorded a conversation with Joyce: "'Who are Sir Lout and his family?' I asked. 'The people who did the rough work at the beginning?' 'Yes,' said Joyce. 'They were giants right enough, but weak reproductively. Fasolt and Fafner in Das Rheingold are of the same breed, sexually weak as the music tells us. My Sir Lout has rocks in his mouth instead of teeth. He articulates badly.'"
Some of Lout's bad articulation ("Feefawfum. I zmellz de bloodz odz an Iridzman") makes clear that he derives in part from a common nursery rhyme: "Fee, fie, fo, fum, / I smell the blood of an Englishman. / Be he alive or be he dead, / I'll grind his bones to make my bread." Sir Lout's domestic skills are not quite as highly cultivated as those of the giant English baker. He uses "bones for my steppingstones." Some of those bones, which Stephen stares at "proudly" earlier in Proteus, are "piled stone mammoth skulls."
As Gifford notes, another inspiration for the idea that the wall of boulders was laid down by a giant may be the story of the origin of the Giant's Causeway, an immense array of basaltic columns that tapers off into the sea in Ulster. Legend has it that the giant Finn MacCool was taunted by a giant in Scotland and tossed rocks into the sea so that he could walk over and have it out. Perhaps it makes sense that Joyce's causeway-builder lays his stones toward England, where the nursery rhyme hails from.
Other stories may be floating around in Stephen's teeming brain. Gifford observes that the figure called Lug of the Long Arm was "also a rock thrower, one of whose exploits was the rock death of Balor of the Evil Eye."