Literally, the Sanskrit word Vajrasattva means "the essence of the thunderbolt (vajra)." Vajrasattva thus embodies within himself the entire essence of Vajrayana Buddhism, of which the vajra is the quintessential symbol. Another of his epithets is 'Dharmadhatu,' meaning the essence of religion. As an important archetypal deity, he is visualized both as a Buddha and a Bodhisattva. He is often thought as the primordial teacher and the priest of the five transcendental Buddhas, and is known in Tibetan as Dorje Sempa.
Here he is shown at the center of a mandala, in sexual embrace with his light-hued female partner, Ghantapani. She holds the kapala (skull-cup) and vajra, while he sits serenely in the dhyana asana, holding the vajra at the level of his heart. His left hand clasps the bell. The bell is said to symbolize wisdom and the vajra signifies the means of utilizing this wisdom. Together the vajra and the bell symbolize the fusion of all polarities, including masculine and feminine qualities, in one Enlightened experience.
According to Alice Getty in her book 'The Gods of Northern Buddhism,' this form is only worshipped in secret.