When I Heard the Learn’d Astronomer 

BY WALT WITHMAN

 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 sitting heard the astronomer where he lectured with much applause in the lecture-room,

How soon unaccountable I became tired and sick,

Till rising and gliding out I wander’d off by myself,

In the mystical moist night-air, and from time to time,

Look’d up in perfect silence at the stars.

Considering the title the intelligent reader wants to find out what does the astronomer said, what does the poet think about it and in which the way this experience impressed the poet enough to write a poem about it.Also, the adjective learn'd suggests that the astronomer is someone who has studied and therefore can teach other people something. 

Looking at the layout the reader notice that the poem doesn’t follow a regular pattern, indeed the there is only one stanza of 8 lines.

So the intelligent reader is also curious about the reason why the poet decides to use this structure to communicate his message. This question is a sufficient reason to go on analiyze the text.

The reading experience makes the reader to notice that the first 4 lines begin with the adverb “when”.This repetion creates a kind of refrain and makes the first lines to be read faster.

The first 4 lines create the context, indeed the speaker is listening to an astronomer, explaining facts about stars using several mathematical tools; charts, diagrams, and columns. The audience appreciates his knowledge and ways of explanation

In the 5 line the use of the adjectives tired and sick suggest that the speaker is not interested in the astronomer's explanation, which probably finds boring monotonous.

The poem is filled with lots of figures of speech: there are consonances, like ones in the line 1,that suggests that the speaking voice is talig about something happened in the past, or in lines 2 and 3 that create the  they create the sensation of a mass of objects. There are also some  alliterations , as the one in the 7 line, that creates the atmosphere, and an anaphora in the first four lines, that build the context with a list of events.

The static phase of reflection is interrupted by the poet who begins to move in space. It is curious how, although the poet is moving, the rhythm of these last lines appears slower than the previous ones.The last lines push the reader to reflect, indeed the poet, on the one hand, displays his disinterest in astronomy from the scientific and mathematical point of view, but on the other hand he pauses to look at the stars. So this poem wants to teach us that studying data and figures is important, but the most interesting and fascinating part is to look at something with our eyes and realize how wonderful the nature is.