The poem begins by listing three different kinds of people with different aims or occupations: nuns, hermits, and students. These people all have one thing in common, in that they work and/or live in a very self-contained space:
- Convents, which are houses for particular religious orders, are often attached to churches or are located in remote areas far from society. Nuns who live in convents typically have small, bare rooms.
- Likewise, hermits are people who live simple, isolated lives removed from the rest of society (often for religious reasons). The cell the poem speaks of is not the cell of a prison, but rather refers to a single room.
- The student’s “citadel,” meanwhile, refers to a raised room, perhaps in the tower of a university or in some kind of academic building. That this citadel is "pensive," or thoughtful, emphasizes the fact that it's a place for quiet study and reflection.
None of these spaces is particularly glamorous, yet each allows their inhabitants to carry out their purpose: a nun must belong to a convent if she is associated with a particular religious order; a hermit not living in isolation isn’t a hermit at all; and a student cannot be a student without a place to study! For nuns, hermits, and students, then, physical confinement thus provides identity and purpose. These tight spaces free them from distraction and allow them to focus on their aims: becoming closer to God, reflecting on the nature of life, learning, and so forth. As such, none of these people "fret," or worry, about their confinement. For them, such spaces are in fact amenable to deep creativity and freedom.
On the level of form, these opening lines also reflect the relationship between confinement and freedom. The first three lines are composed largely in iambic pentameter, a meter of five iambs (feet with a da-DUM rhythm) per line. This meter is typical of sonnets, yet Wordsworth tweaks things from the getgo.
In strict iambic pentamer, the opening line would look like this, which sounds a bit unnatural:
Nuns fret | not at | their con- | vent’s nar- | row room;
Read in a more natural cadence, the words "Nuns" and "not" would receive stressed beats while "fret" and "at" would not. In other words, the first two feet of the poem are actually trochees—essentially the opposite of an iamb, DUM-da:
Nuns fret | not at | their con- | vent’s nar- | row room;
And her- | mits are | conten- | ted with | their cells;
Varying the meter like this adds emphasis to the speaker's opening declaration that these "Nuns" absolutely do "not" worry about their confinement. Were the poem written in free verse, without any regular meter, such a variation wouldn't stand out quite so much; those opening trochees are all the more striking because the poem then falls back into the expected study drumbeat of iambic pentameter. The poem's structure, then, is precisely what allows the speaker to twist and bend the poem's language in meaningful ways!
Also notice the repetition within these opening lines. The word “and” appears twice: first at the beginning of line 2 and then again at the beginning of line 3. This use of polysyndeton/anaphora sets up a steady, logical structure for the poem.