Arati is a ceremony of light performed at the end of satsang (see http://www.sivananda.eu/en/meditation/satsang.html). It is a ritual which probably originated in the ancient Vedic scriptures of India. Yoga masters advise rituals such as Arati for the purposes of worship and inner purification. During Arati, lights are waved before the different representations of the Divine while mantras are chanted according to various traditions. The Divine is light itself. Camphor is sometimes used during this ceremony, which has a symbolic significance; the light of camphor (which melts as it burns) denotes that the individual ego should melt like camphor, and the Jivatman (individual soul) becomes one with the supreme Light of Lights.