It's the ultimate mystery: What happens when the heart stops beating, the brain ceases to send and receive signals, and a person who was once full of life is said to have passed away?

Cultures around the world offer a variety of answers, many based on the idea of an eternal life—a passage through the pearly gates, a tortured future of endless fire and anguish, a continuing cycle of rebirths, or a merging with the creator.

But beliefs about the next life arose long before today's faiths took root. Throughout human history people have hoped there was something after their brief moment in the vastness of time. And for all they knew, the next world might be infinitely happier than this one. The ancient Egyptians, for instance, believed that the deceased would enjoy all the wonderful things that had pleased them on Earth while never suffering pain or grief, hunger or thirst.

Many ancient cultures—the Qin dynasty in China, the Maya in Mesoamerica, and more—filled tombs with provisions and equipment so the dead could inhabit the great beyond in style and comfort. The deceased of modest means got simple things, of course, like a rough ceramic jar filled with the black Nile mud that symbolized resurrection and rebirth in Egypt. But the rich, powerful leaders of communities were laid to rest with the best that money could buy.