Are the deities thought to actually exist? Deities in the tantric system don’t exist as external entities. They’re expressions of Buddhahood, they are emanations of a particular Buddhist teaching. These deities are peaceful, fearsome, and wrathful; they’re multiheaded and multiarmed, each one suited to the temperament of an individual tantric practitioner. Although the images are visually arresting, they are merely mnemonic devices. For instance, often a deity will have, say, four faces, symbolizing the four Brahma-viharas, the Four Immeasurables—love, compassion, joy, and equanimity—fundamental principles in all Buddhist practice. The four-faced deity is only one very basic example of tantric iconography. The symbols are complex and many, and a single image can contain within it all of the essential Buddhist teachings, including the teachings of the Pali canon and the Mahayana sutras. And each image will often contain a central metaphor. In the case of the Kalachakra painting, for instance, the metaphor is time. The central metaphor, whether it’s death, beauty, fierceness, royalty, or the like, serves as the thematic matrix out of which the symbols emerge. It’s a means of bundling the iconography up into a single motif.
Source: Tantric art – maps of enlightenment
Tantra and Veda: The untold story by Roar Bjonnes