Throughout the play, Synge intentionally alludes to different Irish pagan rituals and rites. The following passage—in which Maurya laments the loss of all of her sons—includes two such allusions:
They’re all gone now, and there isn’t anything more the sea can do to me.... I’ll have no call now to be going down and getting Holy Water in the dark nights after Samhain, and I won’t care what way the sea is when the other women will be keening.
The first allusion here it to the pagan holiday Samhain. Samhain—sometimes referred to as All Saints' Day—is a Celtic festival historically observed around the time of Halloween (and is likely one of the precursors to the modern holiday). It marks the end of the harvest season while simultaneously honoring the spirit world.
The second allusion here is to the practice of keening, a Gaelic grief ritual centered on wailing and singing for the dead. Maurya keens to honor the lives of her sons Michael and Bartley, and members of the town join in. By including both of these Celtic pagan practices in the play alongside Catholic prayer (note the reference to Holy Water in the passage), Synge captures the ways in which colonial Christianity and indigenous pagan spiritualities blended in Ireland.
After Maurya follows Bartley down to the sea in order to give him his bread and a blessing, she returns home and tells her daughters about a vision she had of Michael, using a hyperbole and allusion in the process:
I’ve seen the fearfulest thing any person has seen, since the day Bride Dara seen the dead man with the child in his arms […] I went down to the spring well, and I stood there saying a prayer to myself. Then Bartley came along, and he riding on the red mare with the gray pony behind him […] I seen Michael himself.
The hyperbole that Maurya uses here—“I’ve seen the fearfulest thing any person has seen”—is an intentional exaggeration. Whether she truly believes that seeing the ghost of her son on a horse is the most terrifying sight anyone has ever seen, she describes it as such for dramatic effect. She wants Cathleen and Nora—and Synge wants readers—to understand that Maurya’s vision is a pivotal moment in the story.
Maurya’s description of “Bride Dara [seeing] the dead man with the child in his arms” is an allusion to a story in Irish mythology about a Celtic goddess who sees a dead man holding a child and then loses her son in battle soon after. In having Maurya compare her fear to that of the goddess Bride Dara’s, Synge is hinting at how her son Bartley will soon die the way that Bride Dara’s son died.