The greatest influences on the series were Asian art and history; the characters' various personalities and traits are based on philosophical teachings such as Taoism and Buddhism. In the show, some characters have the ability to manipulate one of the four classic elements of ancient philosophy: Water, Earth, Fire and Air, although the Avatar has the ability to control all four. Each of these employ a different form of martial arts in their fighting choreography: Ba Gua for Airbending, Hung Gar for Earthbending, Northern Shaolin for Firebending, and Tai Chi for Waterbending.<ref name="avatar2/index.jhtml"></ref> These individual styles of martial arts also reflect on the personalities of the user and the nations as a whole. These starkly individual tendencies are explained in eighty-five distinct types of "Jings", or internal energy. For example, Ba Gua employs the "negative jing" to create erratic circular movements and capitalizes on centripetal force and defensive positions while Northern Shaolin follows the "positive jing" and emphasizes brute strength and aggression to generate power. The negative jing reflects Aang's bending styles and his tendency to be unpredictable and extremely carefree, as well as his pacifist and non-aggressive nature.