Compare Decoud's "Like a wall" in the darkness of the Gulf and Charles Gould's wall with letters of fire upon it. Wall imagery in Nostromo corresponds to a character recognizing the "walls" of subjectivity that isolate one soul from another. With Decoud in the Gulf it concerned hiding: he enjoyed being shielded from the sight of others. With Charles Gould it concerned manipulating: it came in the context of him tailoring a letter to flatter Holroyd's subjective vanity. Here, Nostromo has returned to the prototypical spot of his old fidelity, nursing a secret revolt that the other's subjective mindset cannot see or understand. The description of the running spider implies that Nostromo's eyes are actually roving around the wall, suggesting a sense of being trapped by this isolation and dishonesty.