At the beginning of Part 1, Chapter 5, Charles and Sebastian return to Oxford once the summer term has ended. Both men are less than enthusiastic about their current circumstances, depressed at the turn from summer's idle hedonism. Note the sensory imagery Waugh utilizes to communicate the pair's discontent:
Everywhere, on cobble and gravel and lawn, the leaves were falling and in the college gardens the smoke of the bonfires joined the wet river mist, drifting across the gray walls [...].
The autumnal mood possessed us both as though the riotous exuberance of June had died with the gillyflowers, whose scent at my windows now yielded to the damp leaves, smoldering in a corner of the quad. It was the first Sunday evening of term.
“I feel precisely one hundred years old,” said Sebastian.
Charles's description of autumn at Oxford parallels the melancholy Sebastian feels. Given that Sebastian is Charles's only and best friend, this melancholic mood pervades them both. The weather reflects this depressed reality: "wet river mist" hangs in the air, mingling with smoke from smouldering fires. Sebastian complains, in his hyperbolic manner, that such weather makes him feel "precisely one hundred years old." Gone is the youthful joy of his Italian summer. Now, with adult responsibilities imminent and the added pressure of maternal surveillance, Sebastian feels the full weight of age. He does not enjoy it.