Christmas, Part Two: "Earth Grown Old"

Christina Rossetti's best-known poem is usually sung or listened to, not read.  I suspect that many of those who sing or listen to the verses are not aware that they were written by Rossetti.  Here is the first stanza of the poem:

In the bleak mid-winter
   Frosty wind made moan,
Earth stood hard as iron,
   Water like a stone;
Snow had fallen, snow on snow,
   Snow on snow,
In the bleak mid-winter
   Long ago.

Christina Rossetti, "A Christmas Carol," in Goblin Market, The Prince's Progress and Other Poems (1875 edition).  The lines "Snow had fallen, snow on snow,/Snow on snow" are particularly lovely, I think.

The poem was first published in a periodical in 1872.  Rossetti died in 1894.  In 1906, Gustav Holst set the poem to music.

                  Harald Sohlberg (1869-1935), "Mainstreet, Roros" (1904)

The line "Earth stood hard as iron" in the first stanza of "A Christmas Carol" seems to lead naturally to another seasonal poem by Rossetti.

                    Advent

Earth grown old, yet still so green,
          Deep beneath her crust of cold
Nurses fire unfelt, unseen:
          Earth grown old.

          We who live are quickly told:
Millions more lie hid between
          Inner swathings of her fold.

When will fire break up her screen?
          When will life burst thro' her mould?
Earth, earth, earth, thy cold is keen,
          Earth grown old.

Christina Rossetti, Verses (1893).

As I have mentioned on other occasions, a significant amount of Rossetti's poetry consists of devotional verse.  "Advent" falls within that category. Who are the "millions" who "lie hid between/Inner swathings of her fold"? I presume that they may be those who (to quote from another Rossetti poem) are "sleeping at last, the trouble and tumult over."  Beyond that, I am not qualified to opine on the "meaning" of the poem.  Rossetti has a mystical strain that gives much of her religious verse a riddling quality. And one often senses that her non-theological world lies somewhere between the lines as well.

                             Harald Sohlberg, "A View of Vestfold" (1909)