Bow down my soul in worship very low
And in the holy silences be lost.
Bow down before the marble Man of Woe,
Bow down before the singing angel host.
What jeweled glory fills my spirit's eye,
What golden grandeur moves the depths of me!
The soaring arches lift me up on high,
The angels singing in heaven (usually “Gloria in Excelsis”) is an oft-depicted scene in literature. Dante famously has the angels sing “Glory to the Father, the Son and the Holy Spirit!” at the opening of  Canto 27  of the  Paradiso . It’s a worthy, stable image for the speaker to “Bow down before”. 
 
 Gustav Doré’s illustration of the angelic choir 
 This rhyme shows how the sound and structure of the poem are interwoven with its feelings of confusion and obsession. Catergorically speaking, its first two  stanzas  are rhymed in the fairly conventional  abab  format, but “host / lost” is an off-rhyme– the consonants chime but the vowel sounds are different (they’re /ɒ/ and /oʊ/ in the  International Phonetic Alphabet,  respectively). 
 Moreover, the “low / Woe” rhyme modulates on the same “o” vowel, creating further confusion for the reader as the rhymes run into each other rather than distinguish themselves: it is as if the speaker is throwing up a poetic form and an enduring image to try to bring order to the crisis that grips them, when actually these things only render it more intensely.
Saint Isaacs Church Petrograd