This question refers to the poem "When I Hear the Learn'd Astronomer," by Walt Whitman.
Answer and Explanation:
When I heard the learn’d astronomer,
When the proofs, the figures, were ranged in columns before me,
When I was shown the charts and diagrams, to add, divide, and measure them,
When I was sitting heard the astronomer where he lectured with much applause in the lecture-room,
The lines are the first four lines of the poem, in which Whitman uses parallelism. Parallelism consists of repeating a grammatical structure inside a sentence, a paragraph or, in this case, a poem/stanza.
First we can notice parallelism through the repetition of "When I" followed by a verb or verb phrase and then an object in lines 1,3, and 4. We can also notice parallelism in lines 2 and 3, when the speaker lists what was shown to him during the lecture.
The purpose of such repetitions is to convey a sense of boredom. The speaker is not impressed by the astronomer's knowledge at all. He finds all that information quite boring. No wonder he gets up and out of the lecture to go outside, to actually look at the stars and admire their beauty.