A Separate Peace, by John Knowles, is set at Devon school. The first chapters of the novel take place during the summer session, when the war seems far away and the boys all exist in a time of youthful innocence and rules can be broken with impunity (a fact which Finny routinely exploits, of course). Games and sports are common and fun--except when Finny is jounced from the tree.
The winter session is much different. The administration is much less tolerant and insists that the boys adhere to the rules. It is important for the students to practice obedience and follow the rules because the war is a looming presence; the boys are on the precipice of adulthood and they will soon be called on to serve their country.
In the midst of this rather harsh, unbending term, Phineas comes back to Devon and, on a dreary winter Saturday, decides to hold a Winter Carnival. Such a thing (a carnival during a time of rigidity and rule-following) would have been impossible without Finny.
Only Phineas failed to see what was so depressing. Just as there was no war in his philosophy, there was also no dreary weather. As I have said, all weathers delighted Phineas. “You know what we’d better do next Saturday?” he began in one of his voices, the low-pitched and evenly melodic one which for some reason always reminded me of a Rolls-Royce moving along a highway. “We’d better organize the Winter Carnival.”
It is a day of competition, drinking, games, and general rule-breaking; the war is something quite distant and the boys are youthful and happy. The Winter Carnival is symbolic of Finny's temporary victory over the war, a small moment of peace amid the turmoil of war. Even Gene realizes it when he says:
It wasn’t the cider which made me surpass myself, it was this liberation we had torn from the gray encroachments of 1943, the escape we had concocted, this afternoon of momentary, illusory, special and separate peace.
Unfortunately, this moment of victory over the realities of war is short-lived, as the war interrupts the Winter Carnival in the form of a telegram from Leper, who has gone AWOL. Gene continues after reading the telegram:
And it was this ["afternoon of momentary, illusory, special and separate peace"] which drained away as I watched Finny’s face pass through all the gradations between uproariousness and shock.
The Winter Carnival is over and the war is just beginning for all of them.