He is using Parallelism, don't let the quiz fool you.
Answer:
This poem depicts the poet's attempt to motivate himself when their is no hope at all, when the poet writes this poem he has already lost one of his legs. So, in such a situation of mental and physical agony, the poet tries to lift up his courage.
"His mind was crowded with memories; memories of the knowledge that had come to them when they closed in on the struggling pig, knowledge that they had outwitted a living thing, imposed their will upon it, taken away its life like a long satisfying drink."
