Final answer:
Anaphora is identified as the repeated grammatical structure in the poem by W. B. Yeats, used for emphasis and to create rhythmic effect. This device is commonly found in literature and speeches, such as the works of Frederick Douglass, where it underscores important emotional points.
Step-by-step explanation:
The grammatical structure that is repeated in the passage from 'An Irish Airman Foresees His Death' by W. B. Yeats is anaphora. Anaphora is a literary and rhetorical device in which a word or phrase is repeated at the beginning of multiple clauses or sentences. This technique is used for emphasis and can create a strong rhythmic effect. For example, Frederick Douglass uses anaphora in his speech by repeatedly starting sentences with 'O', to emphasize his feelings of disappointment and longing for freedom.
The repeated grammatical structure can be seen across various literary texts, often creating a dramatic and poignant impact. Poets and authors use anaphora to emphasize a particular point or emotion, which also aids in making the text more memorable for the reader.
In summary, anaphora is a powerful device that adds emphasis and rhythm to writing, and can be identified by the repetition of words or phrases at the beginning of successive clauses.