When the Blooms' son Rudolph died in January 1894, only a few days after his birth, he was buried in a wool jacket that Molly had been knitting for him. Both parents think about this occurrence during the course of the novel. Uncannily, Stephen too seems to have some telepathic intimation of it.
According to some of the medieval prose of Oxen of the Sun, the labor cries of Mrs. Purefoy put Bloom in mind "of his good lady Marion that had borne him an only manchild which on his eleventh day on live had died and no man of art could save so dark is destiny. And she was wondrous stricken of heart for that evil hap and for his burial did him on a fair corselet of lamb's wool, the flower of the flock, lest he might perish utterly and lie akeled (for it was then about the midst of the winter) and now Sir Leopold that had of his body no manchild for an heir looked upon him his friend's son and was shut up in sorrow for his forepassed happiness."
In Penelope the sweater calls up grief in Molly too: "I suppose I oughtnt to have buried him in that little woolly jacket I knitted crying as I was but give it to some poor child but I knew well Id never have another our 1st death too it was we were never the same since O Im not going to think myself into the glooms about that any more."
Much earlier in the novel, in Proteus, the sight of a woman walking on the strand with a bag on her arm has caused Stephen to fantasize that she is a midwife and the bag contains "A misbirth with a trailing navelcord, hushed in ruddy wool." His adjective may indicate simply a reddish dye in the wool, but it seems very likely that the bloodiness of the misbirth suggests this color to his imagination. ("Ruddy" often substitutes as a euphemism for "bloody" in British slang. The American Heritage dictionary records the curse "You ruddy liar!" in John Galsworthy's Forsyte saga, and the stage directions for Keith Waterhouse's play Billy Liar note that if the character Geoffrey Fisher is not allowed to say "bloody" all the time, his favorite curse word should be omitted in performance rather than altered to some harmless equivalent like "ruddy.")
The most striking thing about Stephen's phrase, however, is its oblique but unmistakable echo of Bloom's nickname for his son, Rudy. Does Stephen possess some unconscious awareness of the link between wool and the Blooms' deceased infant? And, if so, how may this awareness figure in the association that Bloom forms later in the day between Rudy and Stephen? In Hades he meditates on Simon Dedalus' pride in his living son and on his own misery in having lost his male heir. In the passage from Oxen quoted above, the thought of having lost Rudy makes him think ruefully of Stephen, "his friend's son."