Time is of the essence in The Hours. Some characters, like Richard Brown, Laura Brown, and Virginia Woolf, struggle with the thought that their present circumstances will continue day after day, hour after hour, for the rest of their natural lives. As Richard says to Clarissa Vaughan:
"I don't know if I can face this. You know. The party and the ceremony, and then the hour after that, and the hour after that."
"You don't have to go to the party. You don't have to go to the ceremony. You don't have to do anything at all."
"But there are still the hours, aren't there? One and then another, and you get through that one and then, my god, there's another. I'm so sick." (18.21-23)
The Hours definitely has its melancholy moments, but despite the fact that many of its characters choose to end their lives rather than live through any more painful hours, the novel ends by affirming the value of life. It probably won't surprise you to hear that the novel's ringing endorsement of life comes to us through Clarissa, who thinks:
We live our lives, do whatever we do, and then we sleep—it's as simple and ordinary as that. A few jump out of windows or drown themselves or take pills; more die by accident; and most of us, the vast majority, are slowly devoured by some disease or, if we're very fortunate, by time itself. There's just this for consolation: an hour here or there when our lives seem, against all odds and expectations, to burst open and give us everything we've ever imagined, though everyone but children (and perhaps even they) knows these hours will inevitably be followed by others, far darker and more difficult. (22.80)
"Still," thinks Clarissa, "we cherish the city, the morning; we hope, more than anything, for more" (22.80).
Okay, okay—so that's not exactly a ringing endorsement. Still, it's not nothing. In the end, The Hours suggests that even though our lives are nearly guaranteed to bring us pain at one time or another, the hours of happiness and joy do make it all worthwhile.
Oh, yeah—there's one more teensy little thing you need to know about the title: "The Hours" was the working title that Virginia Woolf gave to the novel that eventually became Mrs. Dalloway (source).