“With canina one smoked to forget the daily hell of the soldier’s life, smoked to forget hunger and suffering. Also to forget death. And totally, but totally, to forget tomorrow.”

Kien is describing the horrible conditions of war. The soldiers are either constantly bored, or in sheer terror, so they smoke to forget. But he is also talking about memory. Memory, Kien says numerous times, is the only thing that sustains him—he writes his novel to delve back into the happy past. This means that the soldiers, without memory, have nothing to sustain them. They have nothing to look forward to, no hope of making good memories. They are trying to kill their memories, and thus themselves, through smoking. The quote is ironic in that Kien spends most of the novel remembering the past. 

“To buoy himself up, Kien sometimes tried to concentrate on uplifting memories. But no matter how hard he tried to revive the scenes, they wouldn’t stay. It was hopeless. His whole life from the very beginning, from childhood to the army, seemed detached and apart from him, floating in a void.”

Before the war ended, Kien saw all his friends die. He was camped in the Jungle of Screaming Souls where most of his regiment had been killed, and he himself had been wounded. The jungle itself was supposedly haunted, and being back there has robbed Kien of any hope. In a firefight just a few days before, Kien had walked, without firing, right into enemy fire, hoping to die. Even the good moments of his life have been corrupted by his memories, by his surroundings, and by his lack of hope.