Surgeons must be very careful
When they take the knife!
Underneath their fine incisions
Stirs the Culprit - Life!
After carefully reading the short poem multiple times, I revealed a deeper meaning behind the poem (or I thought so). The first and third lines are written in trochaic tetrameter. The second and fourth each consist of a trochee and a cretic (/ - /). As Aristotle said, "The trochaic rhythm, again, is too much akin to the comic dance, as may be seen in tetrameter verse, for the rhythm of tetrameters is light and tripping." By using a trochaic tetrameter in the odd numbered lines, Dickinson is bringing focus to the even numbered lines. The ends of lines two and four are both stressed and also rhyme. The stressing and rhyming of "knife" and "Life" also brings focus to these words, perhaps to show how using the knife can be a catalyst of making evidences of life appear. The italicization and capitalization of the word "life" shows that the word is probably of most importance in this short poem. "Life" also seems to be an elaboration of the word "Culprit", which is also capitalized. I think what Dickinson is trying to express through the last line in the context of the entire poem is that "life" only shows when the skin is cut open. You can only truly get to know someone by knowing their life, their strengths and their flaws, by cutting them open. "Underneath their fine incisions stirs the Culprit" creates the image where someone's skin is cut open. Inside the skin, instead of finding flesh, you find energetic particles inside, of all colors of the spectrum and also black and white. This imagery shows how "lively" "life" is; it shows that life is full of movement and excitement.
Dickinson uses a cautionary tone, expressed through the words "must be very careful", "fine", "stirs". The way I interpret it is that Dickinson is insinuating that by cutting open the skin, it is like opening Pandora's box in a way, letting out many bad things – including the culprit, life, but there is also a good things (maybe more than one good thing in Dickinson's case). When you open the box, you may not be ready for what is inside it. Through this poem, I think that Dickinson is trying to convey the idea that in order to see a person's true self, you have to look inside, because you cannot see what someone truly is by looking at their outside. At the same time, you must be cautious about looking at the inside of people, you may not see what you want to see.