There are many links between the action of the novel and the life of the author. Click on the author biography link below to read more about John Knowles' life. In particular, however, it is important to remember that Devon is based on the school that John Knowles went to, Philips Exeter. There was a tree just like the one in the novel, which, when trying to jump from it, John Knowles fell and ended up on crutches for most of the summer of one year. Likewise, there was also a "Super Suicide Society". So if I had to pick one section of the novel it would be this one, that includes some of these elements:

Rigid, I began climbing the rungs, slightly reassured by having Finny right behind me. "We'll jump together to cement our partnership," he said. "We'll form a suicide society, and the membership requirement is one jump out of this tree."

"A suicide society," I said stiffly. "The Suicide Society of the Summer Session."

"Good! The Super Suicide Society of the Summer Session! How's that?"

In this quote you therefore have the suicide society and the tree based in the setting of Devon - three key elements that correspond with the author's own life.