When I Heard the Learned Astronomer.

The title tells us that the writer wants to create expectations reinforced by the syntactic anaphoric structure and by  the ripertition of "when" that  makes suspense  and creates a progressive climax. The verb "to hear" instead of "to listen" makes us understand that the subject of the poem was not interested in what the astronomer said, but heard because he finds in that place, so he is bored. Besides the verbs in the passive form as "were ranged" and "was shown" emphasize the object not the one who assists, reinforce the fact that the subject receives the action. So he’s forced to hear, but not interested at the lesson.

This was the first part, which gives us the image of the heaviness of the lesson compared with the second part characterized by a sense of lightness, tranquility and beauty highlighted by the alliterative sounds "D" "A" "E". infact when he becomes free and went out of the lectured room puts up his head and can appreciate the stars. In the class he was blocked by proofs, figures, columns, diagrams ecc. Semantic field of Maths’ words makes the subject bored, tyred and sick, while the second part gives the idea of freedom.