The combination of health issues has kept the Pope from performing his public duties, including weekly prayers on Sundays, but his doctors have recently said he is alert, joking, and continuing to work, as well as reading messages from well-wishers around the world.

Time-honored rituals, drafted and refined over centuries, allow for ritual mourning and provide order at a dramatic moment of transition.

Concerns over Pope Francis' health have mounted in recent years as have questions about his succession. Here's what we know.