Yuganaddha is the tantric Absolute found in the union of the sunyata and karuna. Yuganaddha is the ultimate goal of all tantric sadhana. It has been said that he who discards karuna and sticks to sunyata alone will never have access to the right path. On the other hand, he who meditates on Karuna alone will never gain liberation, even after thousands of births. It is only he who can mingle the two that will attain neither existence (bhava) nor extinction (nirvana). This is attained through Yuganaddha which is the cessation of all forms of duality.
The concept of Yuganaddha has been clearly elucidated in the fifth chapter of the Pancakrama, called the Yuganaddha-krama. It states that Yuganaddha is the synthesis of notions such as samsara (creative process) and nivitti (absolute cessation), samklesa (phenomenal) and vyavadana (absolutely purified entities), and the perceiver (grahya) and the perceived (grahaka). Terms like Bodhichitta, Prabhasvara etc have been used to refer to it in the Hevajra tantra. It has been said in the text that,
"The absence of distinction between Wisdom and Means (Sunyata and Karuna) is the characteristic of the Innate Radiance (prabhasvara), the supreme perfectly Enlightened Consciousness."
In the Sadhanamala, the union (yuganaddha) of sunyata (female) and karuna (male) is called bodhichitta, which is advaya and is conceived as the neuter gender. In yuganaddha, the bi-polarity is synthesized; one aspect is not negated for the sake of the other. Samsara is not disowned for the sake of nirvana; but the two are reintegrated as the two aspects of one and the same reality. What does stand negated is the notion of duality, distinction and differentiation. These arise from thought constructs and theories about what is real and what is not.
The expressions of Yuganaddha in the text are found in the syllables like `evam` and `hum`, and names like `hevajra`, `Vajrasattva` and `Candali`. It is also symbolized by the flame arising from the lotus, or the moon-crescent, or by the flame arising from the kalasa (jar). In Tibet, it is represented by the Ashoka branch inserted into the ambrosia vase. In Chinese and Nepalese Buddhism, it is indicated by the yinyang symbol.
Iconographically, this notion of union is represented by gods and goddesses in amorous embrace. In Tibetan and Nepalese Buddhism, the union of the bipolar reality is represented in the yabyum iconography. The yabyum is a kind of meditative imagery, a kind of representation of the highest level of absorption or reintegration. In the Hevajra Tantra, Bhagavan is seen in union with his yogini. In the two-armed Hevajra, he is in the embrace of Dombi. In the four-armed Hevajra, he is presented as embracing his Wisdom, Vajravarahi. In the six-armed Hevajra, he embraces Vajrasrinkhala.
In the actual tantric sadhana, the yuganaddha is achieved at least initially through various consecrations. The union of the master with the mudra (wisdom consort), and later the union of the yogi with her, are prescribed as means for the direct realisation of union (yuganaddha). This union may also be achieved purely through the internal union employing pranayama.
