Personification is a literary device whereby an inanimate object is given human or animate qualities. The personification in the poem "Out, Out -" has to do with the saw. The saw is described as something that "snarl(s)," giving it the attribute of a ferocious animal, or a beast. It also "leap(s) out at the boy's hand," again like a wild animal, and its act is given the human quality of intentionality; it leaps out "as if to prove saws knew what supper meant."
Onomatopoeia is another literary device in which words are chosen for their sounds in describing to the subject at hand. In the poem, the writer repeats the words "buzz" and "snarled and rattled, snarled and rattled" to replicate the sounds made by the buzz-saw. The consonants in these words in particular - the "zz" in "buzz," the "rl" in "snarled," and the "r" and "tt" in "rattled" - serve to mimic the inexorable mechanical noise emitted by the saw.
The central themes of the poem are industrialization and death. The mechanical saw contrasts with the idyllic scene of the Vermont countryside, and represents the destruction and dehumanizing capacity of machines. As in the larger issues of war, which uses machines of destruction, and the industrial revolution, the author illustrates the vulnerability of the human individual at the hands of the machines he has created. An inevitable result of this phenomenon is death, often the death of innocents like the young boy, and when death strikes, it too is impersonal, almost mechanical, as those around the boy, "since they were not the one dead, turned to their affairs."