The poem starts out very simply, as the speaker begins to tell a story about how she left home early one morning and walked her dog to the seashore. There is nothing particularly striking about this opening, at least not in terms of the subject. Indeed, the speaker's words seem straightforward and self-evident, preparing readers for what seems like it will be a simple story about a casual morning walk to the ocean.
However, the way that the speaker expresses herself isn't all that straightforward. As is the case in many of Emily Dickinson's poems, dashes divide clauses from one another. In this case, these dashes create a prominent caesura in the middle of the first line, as well as a strong end-stop at the ends of both the first and second lines.
These interruptions give the poem a unique sound, making the speaker appear hesitant, unsure, or disjointed, as if what she's saying isn't quite as straightforward as it might otherwise seem. This, in turn, subtly encourages readers to pay close attention to what will follow these opening lines, as the halting rhythm makes this journey to the sea seem fraught with emotion. In this way, the speaker's unique pacing foreshadows the fact that the poem is actually about much more than an innocent, unassuming walk to the ocean!
These first two lines also establish the poem's use of common meter. This which is a meter in which the lines alternate between iambic tetrameter and iambic trimeter. A line written in iambic tetrameter has four iambs, or metrical feet containing an unstressed syllable followed by a stressed syllable (da-DUM). A line written in iambic trimeter, on the other hand, only contains three iambs. Here's a look at the full meter of lines 1 and 2:
I start- | ed Early | – Took | my Dog –
And vis- | ited | the Sea –
This meter gives the lines a musical and satisfying sound that often recalls religious hymns. In this way, the speaker's tone in these opening lines seems lofty and important even though she's talking about the simple act of walking her dog. Consequently, readers sense yet again that there must be something more significant lurking beneath the surface of these words.