Fire was crucial to survival in the Middle Ages. With electricity and gas-powered devices still far into the future, open flame was the most common source of heat for cooking, industry, and protection against the cold. Fires were a bit more difficult to set in an era before matches, particularly if everything was wet. Fire-steels, flint, or pyrite (struck against iron to produce a spark) might be carried in a leather pouch along with tinder. Tinder could be dried brush, straw, birch bark, rotten wood, pine needles, wood shavings, small twigs, or char-cloth. Char-cloth was made by briefly catching a bit of clean linen on fire, then putting the fire out. The resulting bit of blackened fiber could be saved for later and easily caught fire. Once a fire had been successfully lit, the resulting coals were protected with fire covers or other means. It was more convenient to revive…