Our mighty mother
Mulligan looks at the sea and proclaims, "Our mighty mother!" This phrase, so similar to the Swinburne phrase he has just used, comes from a different writer, the Irishman George Russell, known by the pen (and brush) name "A.E." Thornton cites many appearances of the phrase in Russell's writings, and notes that it refers to "the physical world, or, more specifically, the Earth." Gifford defines the Mighty Mother as “nature in its spiritual aspect.”
Russell was a painter, a poet, a leader of the Theosophy movement in Dublin, a nationalist, an agriculturalist, and an energetic editor of two newspapers: The Irish Homestead and later The Irish Statesman. His writings and paintings recommended the spirituality that could be gained by living close to the land. In Scylla and Charybdis, Joyce represents him as saying that "the earth is not an exploitable ground but the living mother."
In Proteus, Stephen recalls Mulligan's paean to the sea as a "mighty mother," but the sacredness endures some sardonic deflation by association with a flabby midwife whose handbag contains, he supposes, "A misbirth with a trailing navelcord."