We'll let Jean Valjean's gravestone do the talking for us:
"He sleeps. Although so much he was denied,/ He lived; and when his dear love left him, died./ It happened of itself, in the calm way/ That in the evening night-time follows day" (188.8.131.52)
In keeping with Valjean's humble life, he's buried in an unmarked grave in a lonely corner of a Paris cemetery. The lines that close the book, Hugo tells us, were scribbled anonymously on top of his gravestone. They suggest that Jean Valjean had a chance to live, love, and suffer, just like all human beings, and that there's something very peaceful and natural about this cycle of life and death, just as night always follows day.
Just to drive home the whole natural cycle thing, Hugo says that even these lines of poetry were eventually washed off Valjean's gravestone by wind and rain. No matter how much we like to think we'll leave behind a legacy when we die, we all end up in the same place—so we should spend the little time we have on earth loving and helping one another.