How we cite our quotes: Chapter.Paragraph or Chapter.Section.Paragraph (depends on whether or not the chapter had sections - some did not)
Quote #16
They watched the four men climb the steps and disappear from view. For a few minutes the scene was deserted. Then –" (21.218)
The diction here emphasizes how the time travel adventure is sort of like watching a play. Words like "scene" and even "then" let us know how a story is unfolding before Harry and Hermione, who are basically watching from the woods like an audience.
Quote #17
"Hermione – what'll happen – if we don't get back inside – before Dumbledore locks the door?" Harry panted.
"I don't want to think about it!" Hermione moaned, checking her watch again. "One minute!" (22.1.12-13)
As Back to the Future taught us, messing around with time can be very dangerous. Here, Harry and Hermione risk screwing up their own time loop.
Quote #18
"Hasn't your experience with the Time-Turner taught you anything, Harry? The consequences of our actions are always so complicated, so diverse, that predicting the future is a very difficult business indeed [...]" (22.3.42)
This book definitely focuses a ton on the past, but there's also a lot about the future here. Hence, a thematic focus on time itself. Most of our forays into the future are also journeys into the ridiculous, courtesy of quack Professor Trelawney. But Dumbledore, who acts like he's guest-starring on The Universe or an episode of Fringe, points out that Trelawney's profession is actually a tough one. Predicting the future is very hard since it requires accurately reading human behavior. Oddly enough, Hermione is a better predictor of future events, given her intelligence and her perceptiveness, than Trelawney is.