It doesn't matter that Harry's gone. People die everyday! Friends, family. Yeah, we lost Harry tonight. He's still with us, in here. So's Fred, Remus, Tonks, all of them. They didn't die in vain. But you will! Because you're wrong! Harry's heart did beat for us, for all of us. It's not over!

Harry Potter and the Deathly Hallows - Part 2 - Movie - Chapter 1 :
See this quote in the Pensive -