Lifeforce is “cosmic energy.” It is the animating principle of all life. We can observe its workings in nature, as heat, magnetism, or electricity. This energy travels downward from the sun, moon, planets, and stars and upward from the earth, ocean, plants, and trees. In every part of the world, already thousands of years ago, humans have speculated about some kind of life force. In China, it is called qi (also spelled chi), in India prana, in ancient Greece pneuma, in Latin spiritus, and in Hebrew Ruach. There are hundreds of life energy beliefs, which have many similarities. This encyclopedia presents and explains them all. In the introduction, distant origins of human thought are traced, examining how spiritual beliefs and life force ideas emerged, and how they were developed through time.