Vajradhara, the 'Indestructible', lord of all mysteries, master of all secrets, is an exoteric representation of Adi-Buddha, and in this form is believed to reign over the Easter Quarter. According to Mahayana school, it is to Vajradhara that the subdued and conquered evil spirits swear allegiance and renounce all active opposition to the Buddhist faith.
Certain Lamaist sects identified Vajradhara with Vajrasattva, while others looked upon Vajrasattva as an active form of Vajradhara, who was too lost in divine quietude to occupy him directly with the affairs of sentient beings. Others again worshipped Vajradhara as a supreme deity distinct and apart from Vajrasattva. The two greatest sects of Mahayana school: the dKar-hGyu-pa and the dGe-lugs-pa acknowledged Vajradhara as supreme, and looked upon as Adi-Buddha.
He is always represented seated, with lotus posture and wears the Boddhisattva crown as well as dress and ornaments. His arms are crossed on his breast in the vajra-hum-kara mudra holding the vajra and ghanta. He is in dark blue color.
Vajradhara is the primordial buddha, the dharmakaya buddha and is regarded as the highest deity in the Buddhist pantheon. Vajradhara, expresses the quintessence of buddhahood itself. Vajradhara represents the essence of the historical Buddha's realization of enlightenment.
Historically, Prince Siddhartha attained enlightenment under the bodhi tree in Bodhgaya over 2500 years ago and then manifested as the Buddha. According to Buddhist cosmology, he was the Fourth Historic Buddha of this fortunate eon. Prince Siddhartha's achievement of enlightenment, the realization, or wisdom of enlightenment itself, is called the dharmakaya, the body of truth. When he expresses that realization through subtle symbols, his realization is called the sambhogakaya, the body of enjoyment. When such realization manifested in more accessible or physical form for all sentient beings as the historical Shakyamuni Buddha, it is called the nirmanakaya, the body of manifestation.
The dharmakaya, synonymous with Vajradhara Buddha, is the source of all the manifestations of enlightenment. Vajradhara is central to the Kagyu lineage because Tilopa received the vajrayana teachings directly from Vajradhara, the dharmakaya buddha. Thus, the Kagyu lineage originated from the very nature of buddhahood.