What symbols does Yeats use in "Easter 1916"?

Yeats uses stone to symbolize the hard, flinty resolve of the Irish rebels in rising up against their British overlords. In stanza 3, he compares the rebels' hearts to an enchanted stone, with "one purpose alone / Through summer and winter . . . ." Everything else around the stone is changing rapidly, such as the splashing of the horse-hooves in the water and the diving of the moor-hens. But the stone stands still in the midst of it all, firm and unchanging, just like the Irish rebels doing their duty against the British in Dublin.
Note that the rebels are not just symbolized by a stone, but an enchanted stone. It's as if a spell—in this case, the spell of Irish nationalism—has been cast upon them, giving them the strength and the determination to stand firm despite the enormous turmoil surrounding them.
https://www.poetryfoundation.org/poems/43289/easter-1916