They believed that all being is corporeal infused with a creative fire called pneuma. The "pneuma" of the Stoics is the primitive substance which existed before the universe. However, in Greek the word ("pneuma") is neuter. Galen placed the vital pneuma in the heart and the psychic pneuma within the brain. In it, air was inhaled into the lungs where it became the pneuma. The combination of blood and pneuma generated heat. A fourth grade of pneuma may also be distinguished. The other two pneuma were the "pneuma physicon" and the "pneuma zoticon". Pneuma Springs Publishing released the book in March 2013.