Es un larguísimo poema narrativo de Lord Byron, escrito a principlios del siglo XIX.
La expresión consultada ha sido traducida como ¨se refleja¨ en la única versión en castellano que he encontrado (aunque entiendo que hay otras).
No creo que sea válido traducir nada menos que Lord Byron a partir de un fragmento minúsculo y sin un concimiento profundo de este poema en particular (consta de más de 400 estrofas), su obra y la imaginería propia del autor y la época.

https://www.scribd.com/document/473103422/La-Peregrinacion-d...

https://books.google.com.ec/books?id=a0C24xkColQC&printsec=f...

https://englishhistory.net/byron/poems/childe-harolds-pilgri...

Maria Callcott o Maria Graham (nacida en Papcastle, Cumberland, 19/07/1785 y fallecida en Kensington Gravel Pits, Londres, 28/11/1842) y George Gordon Byron (Londres, 22/01/1788-Mesolongi, 19/04/1824), más conocido como Lord Byron, fueron contemporáneos y, según la primera cita que incluyo, Maria “was well acquainted with Lord Byron”. Desconozco si su relación fue solo reflejo de la influencia literaria de él sobre ella o llegaron a conocerse personalmente, lo cual teóricamente habría sido posible, ya que ambos compartieron una misma época.

https://www.gov.br/mre/pt-br/embaixada-londres/sections/cult...
VIRTUAL BRAZILIAN BILINGUAL BOOK CLUB| MARIA GRAHAM | JOURNAL OF A VOYAGE TO BRAZIL, AND RESIDENCE THERE, DURING PART OF THE YEARS 1821, 1822, 1823| LIVRO DIÁRIO DE UMA VIAGEM AO BRASIL DIÁRIO DE UMA VIAGEM AO BRASIL - E DE UMA ESTADA NESSE PAÍS DURANTE PARTE DOS ANOS DE 1821, 1822 E 1823
(…)
The title page of the Journal of a voyage to Brazil, and residence there, during part of the years 1821, 1822, 1823 contains a quotation from Childe Harold's Pilgrimage (1812), Canto the Third, stanza two, lines 5-18 by George Gordon, Lord Byron (1788-1824):
ONCE MORE UPON THE WATERS, YET ONCE MORE, AND THE WAVES BOUND BENEATH ME AS A STEED THAT KNOWS HIS RIDER.
These lines provide an insight into the wild beauty of Nature and the Romantic themes of solitude, melancholy, and the transience of life, very apt for her Brazilian journal. It was inspired by Lord Byron’s travels in Southern Europe. Childe Harold's Pilgrimage contains four Cantos, and the third and the fourth are regarded as its best. The word ‘Childe’ was the medieval title for a young squire about to take his vows of knighthood. Maria Graham was well acquainted with Lord Byron.

Y este es el análisis literario del texto Childe Harold´s Pilgrimage de Byron:
https://poemanalysis.com/lord-byron/childe-harolds-pilgrimag...
Childe Harold’s Pilgrimage by Lord Byron
‘Childe Harold’s Pilgrimage’ by Lord Byron was published between 1812 and 1818. It’s a long narrative poem. It extends to 555 pages and 1674 lines in its full publication. Some consider the piece to be autobiographical. It certainly contributed to the image of Byron (George Gordon) as a wandering Romantic. It was likely inspired by Byron’s travels through the Mediterranean and Portugal in the years before he started writing the piece. The poem is dedicated to “lanthe,” a loving nickname he used for Charlotte Harley, the daughter of the 5th Early of Oxford. After the first parts of the poem were published, Byron was thrust into the public spotlight.

Stanza 183
Thou glorious mirror, where the Almighty's form
Glasses itself in tempests; in all time,
Calm or convulsed -- in breeze, or gale, or storm,
Icing the pole, or in the torrid clime,
Dark -- heaving; -- boundless, endless, and sublime --
The image of eternity -- the throne
Of the Invisible; even from out thy slime
The monsters of the deep are made; each zone
Obeys thee; thou goest forth, dread, fathomless, alone.

The speaker addresses the ocean in the next stanza, describing how the IMAGE OF GOD IS REFLECTED IN ITS WATERS. There, one can find God and find eternity, NO MATTER IF THE WATERS ARE CALM OR CONVULSED. God is there through the dark and joyful times. The final lines of this stanza appear to be an allusion to ‘The Rime of the Ancient Mariner. ’The words “monsters” and “slime” are out of place in regards to the rest of the poem, perhaps suggesting, but delving into, the darker parts of the ocean that Harold clearly holds so dear. The ocean commands all that’s within it, he says.