In Hindu mythology, the vajra or thunderbolt is wielded by Indra, the King of the Gods. The word is Sanskrit and literally means "thunderbolt" or "diamond". The Tibetan equivalent is dorje. The vajra has various qualities: (1) it is indestructible, being the most powerful thing in the cosmos; (2) it cannot be used inappropriately; (3) it always returns to its wielder. The vajra represented the natural phenomenon of lightning, similar to the thunderbolt wielded by Zeus. In the Tantric phase of Buddhism, the vajra became a symbol for the nature of Reality, or sunyata, indicating endless creativity, potency, and skilful activity. The term vajra gives the third great phase of Buddhism its name, the Vajrayana, and is employed extensively in Tantric literature: the term for the spiritual teacher is the vajracarya; instead of bodhicitta, we have vajracitta, and so on. The practice of prefixing terms, names, places, and so on by vajra represents the conscious attempt to recognize the transcendental aspect of all phenomena; it became part of the process of "sacramentalizing" the activities of the spiritual practitioner and encouraged him to engage all his psychophysical energies in the spiritual life.
The (instrument symbolizing) vajra is also extensively used in the rituals of the Tantra. It consists of a spherical central section, with two symmetrical sets of five prongs, which arc out from lotus blooms either side of the sphere and come to a point at two points equidistant from the centre, thus giving it the appearance of a "diamond sceptre", which is how the term is sometimes translated.
Various figures in Tantric iconography are represented holding or wielding the vajra. Two of the most famous of these are Vajrasattva and Vajrapani. Vajrasattva (lit. vajra-being) holds the vajra, in his right hand, to his heart. The figure of the Wrathful Vajrapani (lit. vajra in the hand) brandishes the vajra, in his right hand, above his head.
