All living things are surrounded and permeated by vital energy that the ancients in several traditions called "life force". Prana is that the Sanskrit word for that vital force that sustains us physically, emotionally and mentally. it's known by different names in many cultures. “Prana” is that the energy that's moved in Yoga, the “mana” utilized by kahunas for healing, the “chi” that's manipulated in acupuncture and generated in t'ai chi, and it's the “ki” wont to defend oneself in martial arts like Aikido. it's the "Ruah" or "manna" mentioned within the bible and what the Greek philosophers called "pneuma".