The first part of the quote matches with the first story, The Things They Carried. The story told about the items that each soldier took with them to the war. The quote says that the past has a strong grip on the present. The items that the soldiers have with them remind them of there past. Sometimes the soldiers have to let go of something they have because of certain conditions. For example Jimmy Cross had a good luck from his girlfriend Martha, it was a pebble that was from the Jersey shoreline. She sent it to him because it reminded her of how they are "together but separate". Jimmy took this everywhere during the war and kept it in his mouth. When one of his friends got killed during action he got rid of the pebble because he thought it was a distraction.
The second part of the quote, which says, "Where machines seemed sometimes to have more will power than me" Relates to the story "The Man I Killed". In this story the author talks about the man he killed. He starts out by describing the dead person then he starts to regret it. The quote states than in war a machine, which could be a gun, sometimes has more power than a person does. The author noticed this after he killed the enemy soldier, he noticed that it was the gun that killed the person and not him. This made him feel better after a while, but never forgot about the person he killed.
The war story named "Sweetheart of the