Why is Coleridge's use of language important?

“The Rime of the Ancient Mariner” is noted for its musicality and vivid imagery in creating the poem’s fantastic, dreamlike atmosphere. Numerous poetic techniques—alliteration, repetition, distinct patterns of rhythm and rhyme, and various types of figurative language—are found throughout the work. Simile, metaphor, and personification are consistently employed in creating the many memorable images in the poem. Moreover, figurative language and sound devices are often concentrated in particular stanzas to enhance the poetic effect.
This stanza in Part II illustrates the effectiveness of Coleridge’s concentrated poetic language:
About, about, in reel and rout
The death fires danced at night;
The water, like a witch’s oils
Burned green, and blue and white.
The rhythm in the stanza is perfect, with lines of iambic tetrameter alternating with lines of iambic trimeter, each syllable in each line fitting the meter of the line. The end rhyme, “night” and “white,” rhymes perfectly to the ear. The stanza begins with the repetition of “about,” and the musical effect is enhanced through the alliteration that follows. Each of the four lines features words that alliterate: “reel” and “rout,” “death” and “danced,” “water” and “witch’s,” and “burned” and “blue.”
The image in the stanza—St. Elmo’s fire illuminating the ocean—is created through personification, metaphor, and simile. The natural phenomenon is a “death fire.” It dances in a “reel and rout,” suggesting its frightening intensity. The water surrounding the ship burns like the oil a witch would use to cast a spell. The effect of the figurative language is heightened through the negative connotations of “death,” “witch,” and “burned,” words that suggest darkness, evil, or destruction.
The stanza, like “The Rime of the Ancient Mariner” in its entirety, illustrates Coleridge’s artistry as a poet and the power of poetic language to captivate and enthrall.