The "little bat" that makes a crepuscular appearance in Nausicaa receives naturalistic representation in Gerty's portion of the chapter: "a bat flew forth from the ivied belfry through the dusk, hither, thither, with a tiny lost cry"; "something queer was flying about through the air, a soft thing, to and fro, dark"; "there was none to know or tell save the little bat that flew so softly through the evening to and fro." But when the bat enters Bloom's thoughts, observations of its physical properties become mixed with metaphysical speculations about its likeness to a human being. The truncated form of "bat" that Bloom uses four times, "Ba," is an Egyptian term for a part of the human soul, its personhood, that lives on after death.
The ancient Egyptians believed in several different components of the human soul. The most essential and universally possessed of these, the Ka and the Bâ, left the body at the time of death and could reunite to let the individual survive extinction. The Ka was the vital essence, spirit, or spark that animated the body, making it a living thing. The Bâ, typically depicted as a bird with a human head hovering over the body of the deceased or flying away to join the Ka, was the individual personality or character. Food and drink offerings sustained the Ka, and priests performed rites to break the Bâ's attachment to its corporeal body, so that the two spiritual principles could unite once again in the afterlife.
Bloom's thoughts' oscillate between feeble efforts to understand the behaviors of bats and wild fancies that the one flitting about the beach may be a little man released from his human body and changed into an animal form: "Ba. What is that flying about? Swallow? Bat probably. Thinks I'm a tree, so blind. Have birds no smell? Metempsychosis. They believed you could be changed into a tree from grief. Weeping willow. Ba. There he goes. Funny little beggar. Wonder where he lives. Belfry up there. Very likely. Hanging by his heels in the odour of sanctity. Bell scared him out, I suppose. . . . Ba. Again. Wonder why they come out at night like mice. They're a mixed breed. Birds are like hopping mice. What frightens them, light or noise? Better sit still. All instinct like the bird in drouth got water out of the end of a jar by throwing in pebbles. Like a little man in a cloak he is with tiny hands. Weeny bones. Almost see them shimmering, kind of a bluey white. . . . Ba. Who knows what they're always flying for. Insects?" The prominence of birds in these sentences strengthens the impression that the bat may be a Bâ.
If one reads "Ba" as implying thoughts about personal immortality consistent with Bloom's thoughts about "Metempsychosis" and metamorphosis, then there is one obvious candidate for the identity of the "little man." In the previous chapter, Cyclops, a section of narrative parodying Theosophical ideas of the afterlife has featured Paddy Digman commenting on his living conditions in the astral realm and on his continuing attachments to his home and family. Nausicaa takes place on a section of beach very near Dignam's Sandymount house, which Bloom has just left after visiting his widow. In its characteristically jocoserious way, the novel seems to be inviting speculation that Dignam may still be hovering over his earthly stomping grounds.