The victory of Lord Ram over demon Ravana
The most well-known story behind Diwali is written in the Hindu epic, Ramayana. According to Ramayana, Ram, the prince of Ayodhya was ordered an exile by his father, King Dasharath, for a period of fourteen years. Joined by his devoted wife Sita and younger brother Lakshman, he left Ayodhya. During the last year of their exile, Ravana, the demon king of Lanka abducted Sita and took her away to his island kingdom, through deceitful manners. Rama fought against Ravana and his army to free his wife from his clutches and eventually killed him. He rescued Sita and returned to Ayodhya after fourteen years. Their return was celebrated as a grand festival; people lit up their houses with earthen lamps (diyas), burst crackers and decorated the entire city. Since then Diwali is celebrated with bright of the brightest lights, lamps, diyas, fireworks etc.
The Return of Pandavas
Another well-known story associated with Diwali history is narrated in the Hindu epic, ‘Mahabharata’. It says how the five brothers, the Pandavas, suffered a defeat in the hands of their brothers, the Kauravas, in a game of dice. As a rule imposed on them, the Pandavas had to serve a term of 13 years in exile. When the period was over, they returned to Hastinapura on ‘Kartik Amavashya’ (the new moon day of the Kartik month). The five Pandava brothers, their mother and their wife Draupadi were regarded by their devotees as honest, kind, gentle and caring. To celebrate the joyous occasion of their return to Hastinapura, the common people illuminated their state by lighting bright earthen lamps everywhere. Many still believe that the tradition of celebrating Diwali is in remembrance of the Pandava brothers' homecoming.
The rise of Goddess Laxmi
It is also believed that on this very day, the Goddess of wealth, Lakshmi rose up from the ocean. As per the Hindu scriptures, long ago both Devas (gods) and Asuras (demons) were mortals. They had to die sometime or other, like us. But they wanted to live forever. So they churned the ocean to seek Amrita, the nectar of immortality (an event mentioned in the Hindu scriptures as "Samudra-manthan"), during which many divine objects came up. Prime among these was Goddess Lakshmi, who arose on the new moon day (amaavasyaa) of the Kartik month (as per Hindu calendar). On the same day, Lord Vishnu married her. This holy occasion was celebrated by illuminating bright lamps. Every Diwali, Hindus celebrate the birth of the goddess Lakshmi and her marriage to Lord Vishnu on Diwali and seek her blessings for the coming year.
The three demands of Lord Vamana
The origin of Diwali also refers to the stories narrated in the Hindu Puranas, the primary source of Hindu religious texts. According to the Bhagvata Purana (the most sacred Hindu text), King Mahabali was a powerful demon King who ruled the earth. Once Mahabali got a boon from Lord Brahma that made him unconquerable, and he remained victorious over Gods too in many battles. Finding no way to defeat Mahabali, the Devas went to Lord Vishnu and insisted him to find a way to stop him. On Kartik day, Lord Vishnu disguised himself as a dwarf Brahmin (commonly termed as his ‘Vamana’ avatar) and approached Mahabali for some charity. A large-hearted king, Mahabali tried to help the Brahmin and offered him to fulfill his three wishes. Lord Vishnu asked for his kingdom, wealth and Mahabali himself to donate among ultimately the King had to give up all his kingship and wealth. Diwali celebrates this defeating of Mahabali by Lord Vishnu.
The tale of Goddess Kali
According to another legend, long ago after the gods lost in a battle with the demons, Goddess Durga took birth in the form of Goddess Kali to save heaven and earth from the growing cruelty of the demons. After killing all the devils, Kali lost her control and started killing anyone who came her way. Lord Shiva took the responsibility to intervene her. It is said that in her act of killing anyone and everyone, Goddess Kali stepped on Lord Shiva and stops in horror. Her moment of repentance is depicted in all her pictures and statues with her tongue hanging out. This memorable event has been commemorated ever since by celebrating Kali Puja, which is observed in several parts of India in about the same time as Diwali.