The first line of "My Life had stood - a Loaded Gun -" launches the poem into its extended metaphor through its striking introduction comparing the speaker's "life" to a "Loaded Gun." Note that the speaker is not just a gun, but a loaded one, a difference that suggests a dormant capacity for destruction.
Dickinson's use of capitalization to emphasize the two parts of the metaphor ("My Life" and "Loaded Gun") visually reinforces the comparison, while the dashes before and after "a Loaded Gun" literally sets this phrase apart from the rest of the line. This emphasis is also made through the first line's rhythm: the line is made up of regular iambs (poetic feet with an unstressed-stressed beat pattern), but this steady rhythm is partially interrupted by the caesura created from the dash before "a Loaded Gun":
My Life had stood - a Loaded Gun -
This caesura forces a pause in the middle of the line, and in doing so emphasizes the importance of the "Loaded Gun." Dickinson also uses consonance to great effect in this line, with the heavy, thunking /d/ sounds almost mimicking the sound of a plodding, 19th-century gun.
My Life had stood - a Loaded Gun -
Another dash functioning as a caesura breaks up line 2:
In Corners - till a Day
The purpose here seems to be a dramatic shift, separating before and after that fateful "Day" that ends line 2. The enjambment between lines 2 and 3 then adds speed and urgency to the phrase "till a day," which, even without the enjambment, already conveys anticipation. That enjambment pushes the reader straight into line 3 and the introduction of the character of the "The Owner," who transforms the speaker by noticing her (she has been "identified"), and then "carrie[s]" the speaker "away."
As in the first line with "a Loaded Gun," line 3 uses dashes to set off "identified," adding extra emphasis to the word. This implies being noticed—seen—was of great importance to the speaker. The consonance continues from the first line as well, the thudding /d/ sound echoing in lines 2-4: "till a Day / The Owner passed - identified - / And carried ..." Finally, this first stanza is one of only two in the poem that rhyme. In this stanza, Dickinson uses an ABCB rhyme scheme: "Day" ends line 2 and "away" ends line 3.
Altogether this stanza expands on the loaded gun metaphor, as the speaker recounts an empty and powerless existence before the appearance of the Owner. This implies that the speaker has been lying idle until—depending on the reading—the speaker’s anger, God, creative muse, or otherwise gains control. To that end, the speaker describes being alone and useless, hidden away “In Corners” until the Owner “carried [the speaker] away.” This image serves to highlight the speaker’s lack of agency, as the speaker is taken by, rather than leaves with, the Owner.