Don Gifford correctly establishes that Joyce’s headline in Aeolus owes its present form to several sources. He cites two possible influences. The first is Thomas Moore’s song “Let Erin Remember the Days of Yore” (“Ere her faithless sons betrayed her”), which includes the lines:
When her kings, with standard of green unfurled,
Led the Red Branch Knights to danger
Ere the emerald gem of the western world
Was set in the crown of a stranger
Dear Erin, how sweetly thy green bosom rises!
An emerald set in the ring of the sea.
He also appropriately draws attention to “John of Gaunt’s praise of England in Shakespeare’s Richard II” (act 2, scene 1):
This precious stone set in the silver sea.
Joyce’s adaptation of a quotation
For Joyce, this was not a direct quotation, but an expression which held an accumulation of resonances built up over Ireland’s recent history. It is dangerous to attempt to “explain” “ERIN, GREEN GEM OF THE SILVER SEA” (not yet found earlier as an independent quotation), since Joyce’s first “placard” version of this was much shorter: “Erin, the Gem of the Sea”.1
The metaphor of Ireland as a “gem” was a favourite one of Thomas Moore. An early and influential instance occurs in the second stanza of “Remember Thee”, cited here from the 1821 edition of his Irish Melodies:
Wert thou all that I wish thee, great, glorious and free,
First flower of the earth, and first gem of the sea,
I might hail thee with prouder, with happier brow,
But, oh! Could I love thee more deeply than now?2
This text is more relevant, it would seem, than those proposed above. Moore’s line was rapidly taken up and re-quoted, especially by Daniel O’Connell and his supporters:
Mr. O’Connell concluded by professing his determination, as far as his feeble services would go, to employ them in the advancement of his country’s freedom, and expressing his hope that he should soon see Ireland as she ought to be,
"Great, glorious, and free,
The first flower of the earth, the first gem of the sea."
Freeman's Journal (1825), 10 June
Quotations do not have to be exact, and in fact they gain their force by adapting to new contexts and new generations. The association of Ireland, the gem, and the sea was a powerful one for nationalists and others, and variations soon appeared. The London Morning Chronicle notices the allusion in 1828:
Never have these kind orators told them this; but have talked to them about "Green Erin", about the "gem of the sea", about their being bondsmen and slaves.
Morning Chronicle (1828), 1 November
The same theme is picked up by “Henricus” in The Casket of 1828:3
FAREWELL TO ERIN
Farewell lovely Island, thou pearl of the Ocean,
I wander an exile and stranger fromn thee,
I leave thee, but still in my heart’s warm emotion,
I’ll think of sweet Erin, the "gem of the sea".
Another valedictory of 1855 chooses similar wording:
FAREWELL TO THEE, ERIN
By Winny Woodbine […]
How oft by the streamlet I’ve wandered at even,
To gaze on the glory that shone from the heaven –
Till my heart, in its loving, deemed the stars ne’er could be
As bright elsewhere as in Erin, the gem of the sea.4
The Gem of the Ocean
Adrian Room picks out “Gem of the Sea” as a romantic name for Ireland, parallel to the “Gem of the Ocean”, mainland Britain.5 Not surprisingly, there is some crossover between the two expressions. “Gem of the Ocean” and variants seems to have been associated with St Patrick’s Day toasts to Ireland from America. J. D. Crimmins cites the Columbian of 20 March 1811 in this context, and introduces “green gem”, as in Joyce:
Ireland – "Green gem of the ocean’s ring". May your regenerated harps once more be struck to the sound of joy, and your hills and vales echo with the shouts of emancipated man.
J. D. Crimmins, St. Patrick's Day: Its Celebration in New York and Other American Places (1902), p. 165
Caesar Otway appropriates this metaphor to Ireland, not England, in his Sketches in Ireland:
A line of dark demarkation that surrounds the bay [of Glengariff] […] gives a curious sort of relief, (somewhat like the black frame of a brilliant picture;) to the green translucent waters of this gem of the ocean.6
This expression is turn is attributed back to Moore:
This Isle of France [i.e. Mauritius] is what Mr. Moore would call a gem of the ocean. It is all beauty and brilliancy.7
Mixed metaphors throughout the nineteenth century and beyond
This loose variation continued throughout the nineteenth century, with references to emerald, green gem, the sea, and the ocean frequently combined in free permutation. Joseph Carpenter’s Highland Songster compares Scotland with England and Ireland:
I have trod merry England, and dwelt on its charms:
I have wandered through Erin, the gem of the sea;
But the Highlands alone the true Scottish heart warms,
Her heather is blooming, her eagles are free,
Then hurrah for the Highlands, [etc.].8
The popular magazine Judy encourages optimism:
Keep up your pecker, green gem of the ocean,
Chamberlain’s coming to set you to rights.9