I also stumbled on this amazing writtting from Swami Sivananda. You can find it at : http://www.dlshq.org/religions/deepavali.htm
Sri Swami Sivananda
DEEPAVALI or Diwali means "a row of lights". It falls on the last two days of the dark half of Kartik (October-November). For some it is a three-day festival. It commences with the Dhan-Teras, on the 13th day of the dark half of Kartik, followed the next day by the Narak Chaudas, the 14th day, and by Deepavali proper on the 15th day.
There are various alleged origins attributed to this festival. Some hold that they celebrate the marriage of Lakshmi with Lord Vishnu. In Bengal the festival is dedicated to the worship of Kali. It also commemorates that blessed day on which the triumphant Lord Rama returned to Ayodhya after defeating Ravana. On this day also Sri Krishna killed the demon Narakasura.
In South India people take an oil bath in the morning and wear new clothes. They partake of sweetmeats. They light fireworks which are regarded as the effigies of Narakasura who was killed on this day. They greet one another, asking, "Have you had your Ganges bath?" which actually refers to the oil bath that morning as it is regarded as purifying as a bath in the holy Ganges.
Everyone forgets and forgives the wrongs done by others. There is an air of freedom, festivity and friendliness everywhere. This festival brings about unity. It instils charity in the hearts of people. Everyone buys new clothes for the family. Employers, too, purchase new clothes for their employees.
Waking up during the Brahmamuhurta (at 4a.m.) is a great blessing from the standpoint of health, ethical discipline, efficiency in work and spiritual advancement. It is on Deepavali that everyone wakes up early in the morning. The sages who instituted this custom must have cherished the hope that their descendents would realise its benefits and make it a regular habit in their lives.
In a happy mood of great rejoicing village folk move about freely, mixing with one another without any reserve, all enmity being forgotten. People embrace one another with love. Deepavali is a great unifying force. Those with keen inner spiritual ears will clearly hear the voice of the sages, "O Children of God! unite, and love all". The vibrations produced by the greetings of love which fill the atmosphere are powerful enough to bring about a change of heart in every man and woman in the world. Alas! That heart has considerably hardened, and only a continuous celebration of Deepavali in our homes can rekindle in us the urgent need of turning away from the ruinous path of hatred.
On this day Hindu merchants in North India open their new account books and pray for success and prosperity during the coming year. The homes are cleaned and decorated by day and illuminated by night with earthern oil-lamps. The best and finest illuminations are to be seen in Bombay and Amritsar. The famous Golden Temple at Amritsar is lit in the evening with thousands of lamps placed all over the steps of the big tank. Vaishnavites celebrate the Govardhan Puja and feed the poor on a large scale.
O Ram! The light of lights, the self-luminous inner light of the Self is ever shining steadily in the chamber of your heart. Sit quietly. Close your eyes. Withdraw the senses. Fix the mind on this supreme light and enjoy the real Deepavali, by attaining illumination of the soul.
He who Himself sees all but whom no one beholds, who illumines the intellect, the sun, the moon and the stars and the whole universe but whom they cannot illumine, He indeed is Brahman, He is the inner Self. Celebrate the real Deepavali by living in Brahman, and enjoy the eternal bliss of the soul.
The sun does not shine there, nor do the moon and the stars, nor do lightnings shine and much less fire. All the lights of the world cannot be compared even to a ray of the inner light of the Self. Merge yourself in this light of lights and enjoy the supreme Deepavali.
Many Deepavali festivals have come and gone. Yet the hearts of the vast majority are as dark as the night of the new moon. The house is lit with lamps, but the heart is full of the darkness of ignorance. O man! wake up from the slumber of ignorance. Realise the constant and eternal light of the Soul which neither rises nor sets, through meditation and deep enquiry.
May you all attain full inner illumination! May the supreme light of lights enlighten your understanding! May you all attain the inexhaustible spiritual wealth of the Self! May you all prosper gloriously on the material as well as spiritual planes!