9. The Highest Yoga Tantra

Generally, a practitioner should have achieved a realization of emptiness before being initiated into Highest Yoga Tantra^[1]. This inner Tantra, furthermore, has Father, Mother and Non-dual Tantras. The division is based on the three initiations that practitioners receive and practice to awaken and ripen their faculties to achieve the completion stage of the Tantra practice^[2]. Practices involving secret initiations are classified under Father Tantra, those associated with wisdom initiation teaching are under Mother Tantra, and others are under non-dual Tantra. Kalachakra Tantra, Guhyasamaja and its 32 deities' mandala, and Heruka mandala are some of the major practices undertaken in this class of Highest Yoga Tantra.

Completion stages of the Yoga Tantra cover six major steps^[3] of 1) body isolation, 2) speech isolation, 3) mind isolation 4) illusory body, 5) mini clear light, and 6) union of clear light and illusory body. In Sutrayana, emptiness is realized at the grosser level of mind, whereas in the Highest Yoga Tantra of Vajrayana teaching, it is through the subtlest level of mind that emptiness is realized^[4]. One of the distinctive features in Tantra is the deployment of subtle mind and subtle energy. Realization of emptiness or the objective clear light is there in Sutrayana, but realization of subtle mind or subjective clear light is exclusive to Vajrayana. Buddhahood or Dharmakaya is activated with the union of this objective clear light (wisdom of emptiness) and subjective clear light (extremely subtle clear light mind). The practice is known as rdZog chen in the Nyingma (old) School of Tibetan Buddhism; Mahamudra [Tib:Phyag rgya] in the Kagyu tradition; Primordial Innate Clear Light [Tib:gNyug ma lhan cig skyes pa'i 'od gsal] in the Gelug School, and Union of Clarity and Emptiness [Tib:gSal stong 'zin] in the Sakya tradition. It is also found in Bon^[5] Tibetan religious tradition. This Highest Yoga Tantra strongly emphasizes exploring and activating the subtle mind to realize subjective clear light to remove the innate afflictions or contamination completely.