When I heard the learn'd astronomer

The title prepears the audience for something special, linked to science and especially to astronomy.

From the title we can imagine that the story is about someone who heard the learnd astronome and from the verb "heard" we can understand that the writer isn't involved in the astronomer's speech. Because "heard"dosen't mean willingly listen to what someone told us.

The poem is in free verse : it is made up of  8 lines. The firs four lines are about the writer's memory  about the astronomy  lecture. With the anaphorical repetition of "when" at the beginning  of these lines the reader understands the situation refers to a past action.

In the last four lines are about his feelings during the lecture and when he went he suddenly went out from the lecture room without an apparent title.

This poem is about a boy who is in the lecture room hearing a learned  astronomer explain the numbers, the charts and diagrams when for an unaccountable reason, the poet felt tired and bored. He went out of the room and in the night he looked up to the sky and at the stars.

There are a lot of allitterations like "heard" and "learn'd" or "mystical moist night-air" and the assonance "rising and gliding"that add to meaning.

The deeper meaning is that there are different ways to consder the same thing. In the lecture room the boy was bored for the astronomy lesson, but when he went out he saw the stars and he felt at ease.

A technical attitude may not be better than a natural approach to things: this is what the text may suggest.