Lines 1–2

The title of “Witness” identifies the subject at hand as bearing witness to an event (in this case, the appearance of a comet). The opening words of the poem, “I saw,” stated in the past tense, indicate that the witnessed moment happened in the past and now remains clear in memory.

In the first couplet, readers are also asked to bear witness to the initiation of a metaphor that has both empirical and philosophical connotations. A “star” is compared to a horse breaking the rope that has kept it confined to “the stables.” The rope of dust streams from the comet in the direction away from the Sun which it orbits. Without gravity the Earth (the speaker’s vantage point) would not be held together as one sphere, and its orbit would not be fixed by its...