As one has to take bath after using the toilet, so one has to wash himself with water after sexual intercourse, especially when at a forbidden time. Kasyapa Muni meditated on the impersonal brahmajyoti by chanting the Gayatri mantra within his mouth. When a Vedic mantra is chanted within the mouth so that only the chanter can hear, the chanting is called japa. But when such mantras are chanted loudly, it is called kirtana. The Vedic hymn Hare Krsna, Hare Krsna, Krsna Krsna, Hare Hare/ Hare Rama, Hare Rama, Rama Rama, Hare Hare can be chanted both softly to oneself or loudly; therefore it is called the maha-mantra, or the great hymn.