Going to kick off the discussion.
Looked up analysis of the Yeats poem Who Goes With Fergus, since it plays such an important part in the chapter. This is what I found, and it seems to touch on the dueling forces at play in Ulysses and in Dedalus:
"On one level, the poem represents Yeats' exhortation to the young men and women of his day to give over their political and emotional struggles in exchange for a struggle with the lasting mysteries of nature.... A return to Fergus entails a move away from the reference points of contemporary politics, toward the mythology of the Irish people."
Interesting, especially since I love Greek Mythology and am Irish, but that's a little different from Irish Mythology adding more interesting flavor. :)
By mysteries of nature, does he mean the wisdom and knowledge of the druids?
That sounds like a good possibly. Seems quite fitting enough. Some of the things that fit into these stories is amazing. Hadn't realized this book was going to be more like a puzzle! Will have to read more into this idea.