Diwali is celebrated on the day of Amavasya but the festival is symbolized by inner happiness, lighting or Purnima.Moon in mythology is symbolized by cool positive thoughts. Generally, one encounters negatives thoughts ly on the day of Amavasya and positive thoughts on the day of Purnima. Diwali is the only day in a year where one experiences positive thoughts on the day of Amavasya, hence some people believes Diwali symbolizes Diwali with inner Purnima and outer Amavasya.Diwali celebrations also coincide with the terminal phase of Chaturmas, the four months of negative state of mind.The purification process in Chaturmas starts with the first Navratra falling on Amavasya. During these nine days one undergoes mind, body and soul detoxification by not thinking negative, doing positive things and acquiring soul-based knowledge.The mind-body detoxification during Navratras ends with killing of Tamas (Kumbhakarna), Rajas (Meghnath) and ego (Ravan) and of consciousness (Rama) over the evil.These benefits do not lead to inner Moksha or happiness until 20 days, the day of Diwali. In order to continue getting benefits of Navratras one needs to fast with positive state of mind every fourth day till Diwali.On Sharad Purnima, the fast involves thinking positive with a cool mind to get health benefits. Four days later, on Karvachauth again, one fasts and worships the Moon with positive thoughts and acquires longevity benefits. Four days later on Ahoi Ashtami again, one worships the moon and the stars with positive thoughts and acquires fertility benefits. On the day of Dhanteras one acquires a win over the fear of death (Yama). On this day, the fast involves deeper meditation (Samudra manthan) to get all the benefits of Samadhi.At the end of the meditation in the state of Samadhi, one gets in touch with the consciousness or the God, the insight gets illuminated and a person experiences bliss, a state of ecstasy of inner happiness and that is what is called experiencing inner Purnima on the day of outer Amavasya and the festival is celebrated as Diwali.Let us all worship this Diwali as a state of positive mental state. This one month of purification of thoughts helps one in combating the depression phase seen in winter.Diwali is the only Amavasya where one does not do Shraadh pooja. On Diwali Amavasya (falling in Chaturmas) one is allowed to start any new project. Even deaths on this Amavasya are considered auspicious (unlike on other Amavasya days).(Disclaimer: The views expressed in this write up are my own).