Moxa has a warm nature but in ancient times its nickname was ‘Ice Altar’. This name originated from the way people revered and worshipped the sun. People believed that fire from the sun was sacred fire. So they invented a ritual. They shaped the ice into a thick lens and placed moxa beneath it. According to light refraction theory, the sunlight lit up the moxa. With this ritual they made the ‘sky fire’ flow all the way down to earth. This is the story behind the nickname ‘Ice Altar’.