Srila Bhaktivedanta Narayana Gosvami Maharaja: Dipavali means a time of happiness. When Lord Rama defeated Ravana and reached Ayodhya, a big Dipavali festival was performed there. Sri Vamanadeva wanted to cheat Bali Maharaja. He did not cheat him; rather He gave His mercy, although it seemed that He was cheating. When Bali Maharaja was offered a benediction from the Lord, he requested, “Always remain in my home.” In this way the Lord Himself was “cheated.” Lord Vamanadeva was very glad, and He agreed to stay there forever. Due to great happiness, Bali Maharaja then asked all his associates to hold a Dipavali festival, and that was the first Dipavali. When Krsna defeated Duryodhana and returned to Dvaraka, a Dipavali was also celebrated there.
Lord Krsna Himself, along with Mother Yasoda, Nanda Baba and all the other Vrajavasis, came here to Manasa-ganga, and celebrated this festival with their own hands. In other words they themselves offered dipa (a lighted ghee wick) and rendered many other services.
Dipavali also means light. If there is no bhajana of Krsna there is darkness, and in Krsna Consciousness there is light. We celebrate this function in order to give up darkness and to bring the light of bhakti, pure devotion. This is the same celebration. Real happiness comes from playing karatalas and mrdangas. If one hears this, and if maya hears, maya will go away at once. Sri Caitanya Mahaprabhu brought the saìkirtana movement to this world to drive out maya. Sri Krsna and Sri Caitanya Mahaprabhu celebrate this Dipavali Themselves, and we should try to follow Them.