How does the author use foreshadowing in Sir Thursday?

In addition to establishing contrasting styles, the opening passage is stylistically significant for two additional reasons: (1) it serves as a benchmark by which we can compare Paul's shifting view of reality as the narrative develops; and (2) the passage foreshadows the end of the story. The simile—"it was as if, in some delightful way, his secret gave him a fortress, a wall behind which he could retreat into heavenly seclusion"—changes from a comparative device here to reality for Paul. This kind of simile, which Aiken uses repeatedly, becomes, as it occurs, an indicator of Paul's vision as it becomes increasingly snow laden.