It is a properly repeated hymn or formula used in ritual worship and meditation as an instrument for evoking the presence of a particular divinity; first uttered by an inspired seer (rishi) and transmitted orally from master to disciple in a carefully controlled manner. A mantra may be composed of but a single sound (om), or several syllables. Each deity is represented by its own mantra. It is only by the correct enunciation of the correct mantra that the deity will descend to enter the body of its images or will respond to a devotee. A mantra has great potency and represents the Supreme Being Himself in the guise of sound. The disciple must keep his mantra secret and say it silently as part of his regular worship. Other mantras are openly known and commonly said, e. g. the Gayatri Mantra, which forms part of the morning ritual.