One of the things [Yossarian] wanted to start screaming about was the surgeon’s knife that was almost certain to be waiting for him and everyone else who lived long enough to die. He wondered often how he would ever recognize the first chill, flush, twinge, ache, belch, sneeze, stain, lethargy, vocal slip, loss of balance or lapse of memory that would signal the inevitable beginning of the inevitable end.
This quote from Chapter 17 demonstrates that the war, in confronting Yossarian daily with the possibility of his own death, has not hardened him to fear; instead, it has made him much more aware of the value and fragility of life. He cannot stop thinking about all the ways in which he could possibly die—in addition to antiaircraft fire, there are plenty of diseases that could kill him. In this passage, Yossarian also dwells on the inevitability of death. He feels trapped in the army; Catch-22 prevents him from escaping it. But the fact that he must someday die is an even greater and more inescapable trap, for even if he manages to wiggle out of the prison of the army, he will still have to face his death eventually.