In the Hindu religion, there are two types of ritual, namely Nitya Yadnya and Naimitika Yadnya. Nitya Karma is a ritual held every day on a regular basis. Nitya Karma activities such as Tri Sandya (pray 3 times a day) and Ngejot. Naimitika Yadnya is a ritual performed at a specific time, such as Galungan, Nyepi, Eka Dasa Rudra, rituals at special moments, and also Purnama Tilem ceremony. Balinese people believe that every ceremony / celebration ritual has a meaning as a doctrine of life, including ritual on Purnama and Tilem.
Purnama and Tilem ritual performed every 15 days following the lunar cycle. When the full moon, the Balinese held Purnama ceremony, while the peak of the dark moon, Balinese held Tilem ceremony. The philosophy of the lunar cycle (Purnama and Tilem) taught men that life is always filled with light and dark, good and bad, black and white, life and death, and two other things that will always be opposed or called Rwa Bhineda. Two opposite things will always come to men by turns. We should not be exaggerated when getting happiness. And conversely, do not overdo it when experiencing suffering. Because life will always be like that, there will always happiness and sadness.
On the full moon (Purnama), Hindus worship to Sang Hyang Chandra as the god of moon. When the feast Tilem, the Hindus in Bali adore Sang Hyang Surya as the ruler of the sun. Balinese people believe that at the height of the full moon and the peak of dark moon, clusters of galaxies emit a certain energy that affects the lives of living creatures on earth. Therefore, the people of Bali begged the energy provide positive energy for life. When Purnama and Tilem, Balinese people perform prayers at the family temple, the village temple, or the other temples. Worship is usually done at night, starting at 8 pm.