The opening two lines of “The Caged Skylark” establish the simile that the remainder of the poem explores as an extended metaphor. The premise of this simile can be summed up as: two entities, the skylark and the human soul, are meant to soar to spectacular heights but are instead trapped. The remainder of the poem considers the various consequences of their confinement and the ultimate hope for freedom.
Hopkins’ poetry is well known for its frequent use of repetitive syllables. In these first two lines, we find this repetition in high effect. From the start, the overlapping sounds can feel so crowded on top of one another that they feel trapped, in much the same way that the soul can feel trapped in the body. Since there is an overwhelming amount of repetition in these two lines, only the instances that contribute most prominently to the meaning of the lines will be selected. The description of the skylark as “dare-gale” includes the assonance of two long a’s. Meanwhile, the k of “skylark,” is alliteratively repeated by the hard c in “scanted." And both of those two sounds—the a and the k—are repeated again in the word “cage" at the end of the line. In this way, the very sounds associated with the skylark are themselves, like the skylark, contained in the word “cage." A similar effect can be seen in the way that the s at the start of “spirit” reemerges in “house,” which is the spirit’s cage.
In another way, though, the repetition of sounds quickens the pace especially of the first line, which seems to accelerate until it crashes into the final two syllables, both of which are stressed: “dull cage.” This final spondaic foot abruptly halts the speed of the line, as the cage itself stops the swift movements of the skylark.
In addition to the sounds they contribute, the words themselves convey a complex relation of meanings. While “scanted” is a verb that can mean "to provide for meagerly even to the point of neglect," it is more commonly used as an adjective and would mean "rare or in poor supply." In this way, the skylark, because it is “scanted,” is made into a poor, meager version of itself, but it is also neglected and left to suffer its terrible conditions alone.
There are two prominent ways that the description of the spirit’s cage connects to the description of the skylark’s. First, the spirit dwells in a “mean house.” Here, “mean” can be a synonym of “scant,” referring to the body's impoverished state and its inability to meet the needs of the spirit it houses. Second, the typical image of a birdcage includes thin bars that run from the top of the cage to its bottom. The “bone-house” description, then, also evokes the specific image of the rib cage—while the skylark's cage is a metaphor for the body, the poem here suggests that the similarity in fact may be more literal than it initially appears.