The sight of the "the gunwale of a boat, sunk in sand" makes Stephen think of a zinger of 19th century literary criticism: "Un coche ensablé, Louis Veuillot called Gautier's prose." The French means "A coach stuck in sand."
Théophile Gautier (1811-82), Gifford notes, was "a French poet, critic, and novelist famous for a 'flamboyant' romanticism with overtones of frank hedonism and a 'pagan' contempt for traditional morality." His contemporary Louis Veuillot (1813-83), a journalist and politician, opposed literary romanticism because, Gifford notes, "the French romantics were traditionally anti-Church," and Veuillot was a defender of the Roman Catholic Church's secular powers in France. In an essay published in 1867, Veuillot attacked the romantics and abominated Gautier's prose in particular as weighted down by "superlatives." His metaphor of a coach trapped in sand implies that prose should be light, agile, and adaptable.
Veuillot's phrase may pop into Stephen's mind simply because he sees a boat stuck in the sand, but he uses it to meditate briefly on the protean qualities of language: "These heavy sands are language tide and wind have silted here." Like the many other kinds of matter that combine to make up his life (physical elements, past experiences, family upbringing, national identity, and so forth), language too is a kind of prima materia against whose heavy shifting tug the artist must struggle to impose his shape on the world. In Veuillot's estimation, Gautier lost the battle.
The image of being stuck in the sand will recur later in the novel as a figure evoking the phrase "stick-in-the-mud," i.e. a person trapped in one of life's ruts and unable to act spontaneously. The words that Bloom, at the end of Nausicaa, inscribes in the muck with a stick, "I. AM. . . . A.," combined with the fact that "his wooden pen" sticks upright in the sand when he flings it away, suggests that he is a stick in the mud, as well as confirming Stephen's intuition about language: "Mr Bloom effaced the letters with his slow boot. Hopeless thing sand. Nothing grows in it. All fades." In Eumaeus and Penelope both he and his wife will think of the other as a stick-in-the-mud keeping them from realizing happiness.