In Tsongkhapa's exposition, there are various types of radiance or clear light. One is found in Mahayana sutras and in tantras, but there is an extraordinary radiance which is unique to tantra. The extraordinary radiance exclusive to highest yoga tantra is reached through inner heat practice and illusory body yoga joined with meditation on emptiness. This radiance, also termed "primordial wisdom of ecstasy and emptiness," is the focus of the system of six dharmas. Mullin (2005), p. 82. Tsongkhapa divides the practice of radiance into waking and sleep practices.