It was love at first sight.
The first time Yossarian saw the chaplain he fell madly in love with him.
Yossarian was in the hospital with a pain in his liver that fell just short of being jaundice. The doctors were puzzled by the fact that it wasn't quite jaundice. If it became jaundice they could treat it. If it didn't become jaundice and went away they could discharge him. But this just being short of jaundice all the time confused them.
Each morning they came around, three brisk and serious men with efficient mouths and inefficient eyes, accompanied by brisk and serious Nurse Duckett, one of the ward nurses who didn't like Yossarian. They read the chart at the foot of the bed and asked impatiently about the pain. They seemed irritated when he told them it was exactly the same.
"Still no movement?" the full colonel demanded.
The doctors exchanged a look when he shook his head.
"Give him another pill."

This classic novel of wartime madness goes through three very different stages, and each of them holds up very well.

It starts out as a comedy, filled with clever wordplay, puns and hyperbole similar in style to, say, Douglas Adams. Two particularly amusing patterns that Heller constantly employs are funny non-sequitur lines of reasoning that fly straight into the face of convention or common sense, and conversation threads that abruptly jump around in time, location and participants, which makes for nice momentary confusion.

After a while, it develops into social satire, commenting on the madness of the military machine and war itself. That part probably gained Catch-22 its status as a subversive counter-culture classic in the sixties, but it is still relevant today.

Towards the end of the book, humour makes way for tragedy as the horrors of war are suddenly shown in grim detail: Many characters that have been previously established as comic relief are killed, and the plight of the Italian civilians also becomes apparent in a depiction of Rome that has completely changed in tone from previous chapters.