Final answer:
In Elizabeth Bishop's 'One Art,' the phrase 'the art of losing isn't hard to master' is an example of repetition, which emphasizes the poem's theme.
Step-by-step explanation:
In Elizabeth Bishop's 'One Art,' the literary tool used when repeating the phrase 'the art of losing isn't hard to master' is repetition. Repetition is the simple repeating of a word, within a short space of words, with no particular placement of the words to secure emphasis.
It is a multilinguistic written or spoken device, frequently used in English and several other languages, such as Hindi and Chinese, and so rarely termed a figure of speech.This device serves to emphasize the message of the poem and contributes to its thematic development.
Unlike alliteration, which focuses on the repetition of initial consonant sounds, or metaphors and similes, which establish relationships between different things, repetition reinforces an idea or motif throughout a literary work, as seen in Bishop's poem.