His backward eye
As Bloom raises the window blind in the bedroom he keeps his peripheral vision trained on Molly's perusal of the mail: "his backward eye saw her glance at the letter and tuck it under her pillow." Although the verbal connection is slight, Gifford is almost certainly correct to hear in this sentence an echo of Edmund Spenser's cuckold Malbecco, who cannot escape the awareness of his wife's infidelity: "Still fled he forward, looking backward still."
In book 3, canto 10 of Spenser's The Faerie Queene (1590), Malbecco is a miserly and jealous man who perpetually suspects his wife Hellenore of infidelity. She responds by running off with a flashy knight named Paridell, who abandons her after having his sexual fill, "For having filcht her bels, her up he cast / To the wide world, and let her fly alone, / He nould be clogd. So had he servéd many one" (stanza 35). Hellenore, left to her own devices, enacts an adult version of Snow White by moving in with a band of satyrs, "With them as housewife ever to abide, / To milk their gotes, and make them cheese and bred, / And every one as commune good her handeléd" (36).
Looking for his wife, Malbecco runs into Paridell and, "almost dead with feare," greets him fairly; Paridell tells him that he no longer cares for Hellenore and that she is living somewhere in the forest (37-38). Concerned for his wife's safety, Malbecco plunges into the forest and finds "Faire Hellenore, with girlonds all bespred, / Whom their May-lady they had newly made" (44). When night comes, all the satyrs kiss Hellenore. Malbecco creeps closer, his sprouting cuckold's horns making him indistinguishable among the goats, and watches her current partner perform:
At night, when all they went to sleepe, he vewd,
Whereas his lovely wife emongst them lay,
Embracéd of a Satyre rough and rude,
Who all the night did minde his joyous play:
Nine times he heard him come aloft ere day,
That all his hart with gealosie did swell;
But yet that nights ensample did bewray,
That not for nought his wife them loved so well,
When one so oft a night did ring his matins bell. (48)
Malbecco wakes his wife in the morning and tries to persuade her to return with him, all her trespasses forgiven. She refuses and he ignominiously retreats, at first on hands and knees with the goats, and then rapidly on foot: "Still fled he forward, looking backward still" (56). At last he throws himself off a cliff to die, but jealousy has wasted his substance to nothing and he becomes a purely allegorical monster named Gealosie.
Bloom is neither a miser nor pathologically jealous, but other details of Malbecco's story fit his situation all too well. The satyr's sexual prowess, which shows clearly "That not for nought his wife them loved so well," has obvious relevance to Boylan's ability to satisfy Molly repeatedly in a way that Bloom can no longer manage even once. And Malbecco's timidity before Paridell makes a reader think of Bloom's inability or unwillingness to confront Boylan. Bloom's complicity in the adultery, and Molly's evident desire to have him know what she is doing, are captured in the moment when she very ineffectively conceals Boylan's letter while he simultaneously looks away and gives her "his backward eye," in a kind of sorry inversion of the wish-fulfillment principle.