Instructions
Locate the hospital, which is just north of the Mausoleum.
Drag a villager, adult or child, to the hospital and drop the villager onto the purple-masked heathen.
Wait for the villager to heal the heathen.
Watch the celebration scene, where the heathen converts to a believer. He is now a part of your tribe.
Notice that a collectible appears to the left of the hospital. Drag a child on top of it. This is a piece of a necklace you will need to solve Puzzle 16.
Use the former heathen as your doctor. Open the details menu and place a check mark in the healer position to assign this trade. Drag the new villager to the hospital to encourage him to study medicine.