Lines 1–2

“When I Heard the Learn’d Astronomer” begins by repeating the title, something that often occurs in Whitman’s poetry and gives extra weight to the first phrase, to set up the idea that the speaker is listening to an educated scientist. This phrase also stands out because of its internal rhyme, or rhyme within the same line, of “heard” with “learn’d.” This is also a slant rhyme, or an inexact rhyme, since “learn’d” has an “n” sound unlike “heard,” but it nevertheless emphasizes a sense of repetition. The slant rhyme even gives the first line an impression of awkwardness, since it is difficult to pronounce and uses the same long vowel sound twice in a row.

The other element of the first line to notice is use of the contracted version of “learned.” Whitman frequently contracts words such as this, which would always be spelled out today, partly in an attempt to capture the way people actually spoke, instead of a high prose style. In this context, the contraction places some distance between the speaker of the poem, or the voice of the narrator, and the educated astronomer to whom he is listening. The poet may be suggesting here that the speaker uses a different, perhaps a more common or lower class, style of expression from the learned scientist.

Line 2 of the poem then presents the interesting image of “proofs” and “figures” of mathematical equations “ranged,” or arranged, in “columns.” Notice that the poem’s first four lines become increasingly longer, unlike these columns, which presumably go straight up and down within the same horizontal space. If a poetic line stretches beyond the margin, the standard method of printing that line is to continue it below, after an indentation. If a poetic line is continued in this way, therefore, it does not change the fact that the line should be considered to extend further and further to the right. Thus Whitman is likely to be contrasting the visual poetic expansion in the lines with the columned mathematical expansion of the astronomer’s proofs.

Lines 3–4

The third line, in which the speaker is shown materials related to astronomy and asked to manipulate mathematical equations, is full of mathematical diction, or word choice, such as “charts,” “diagrams,” “add,” “divide,” and “measure.” These words make up almost the entire line, and they are likely to overwhelm the reader, as they will increasingly overwhelm the speaker. That the speaker is asked to “add, divide, and measure” the “charts and diagrams” also emphasizes the negative side of the process, as though the lecture has nothing to do with the sky but merely manipulates its own figures.

This is reinforced by the fact that, through the fourth line, the poem has said nothing about astronomy. The fourth line also emphasizes that the speaker is “sitting,” as opposed to standing or actively engaging with the subject, and stresses again that the lecture is occurring in the “lecture-room,” away from nature. And, once again, the reader is caught up by the internal repetition of “lectured” and “lecture-room,” as is the case in the internal rhyme of line 1. This technique serves to contain the line inside its own words and achieve the stuffy lecture-room atmosphere that Whitman seems intent upon conveying. The applause that the lecturer is receiving therefore does little to make the lecture seem compelling or interesting.

Lines 5–6

Line 5, which comes at the halfway point in the poem, shifts in style from the first quatrain, or unit of four lines. In fact, everything that has come previously in the poem sets up and modifies the statement “I became tired and sick,” which also contains the poem’s first active verb. It is partly understandable from the description of the lecture why the speaker feels this way, but the deeper reason is contained in the word “unaccountable.” Slightly confusing at first because it seems out of place in the sentence, this word primarily means that it is “unaccountable,” or difficult to determine, why the speaker became tired and sick. But there is a strong secondary meaning of the word of great importance to the main themes of the poem; namely, that the speaker has become tired and sick because he is an “unaccountable” person, or someone who is impossible to explain or define.

The speaker then wanders off by himself in line 6, leaving the lecture room, and this line is therefore the turning point in the poem. There are a number of key elements to notice here, including the fact that the first two descriptive verbs, “rising and gliding,” make it seem as though the speaker is flying out into the sky and directly interacting with space. This is an important poetic technique that combines the figurative, or metaphorical and representative, meaning, with the literal meaning, which is that the speaker walks outdoors.

The second important aspect of this line is the fact that the speaker “wander’d” out of the lecture room; this is the first hint that perhaps the speaker is somewhat aimless or unstructured in comparison with the exactness of the learned astronomer. Finally, it is important that the speaker leaves the lecture “by myself,” because this suggests that, unlike the group effort of scientific analysis, the speaker will be approaching the phenomenon of astronomy alone. Like an artist, the speaker will be interpreting the stars on his own terms, as a creative individual.

Lines 7–8

In line 7, the speaker has emerged outside into the “moist night-air,” and the key word in the description of the night sky is “mystical.” This word could suggest a variety of spiritual ideas, from ancient pagan worship to romantic individualism, but it is very distinct from anything scientific, and it establishes a radically different atmosphere from that of the lecture room. The seventh line again uses the technique of internal repetition with “time to time,” but this idiom, or phrase from common speech, is mainly a method of reinforcing the speaker’s more relaxed and unstructured process of observation. By looking up every so often, whenever he desires, the speaker is approaching nature very differently from the scientific regularity of observation and analysis.

It is also important to recognize that, in referring to the “mystical moist night-air,” line 7 contains the first actual image of the sky itself. But even here the speaker has not quite reached the astronomical phenomena themselves, and does not do so until he looks up “in perfect silence” in line 8, again using a contracted “ed” verb, “Look’d,” like “wander’d” in line 6 and “learn’d” in line 1, to emphasize his common touch. Here, in the very last word of the poem, only after the speaker has reached “perfect silence” and just before the words and descriptions of the poem end altogether, the speaker finally sees the vision of the “stars.”