In plain words
The Light of Rāma
The day Śrī Rāma killed Rāvaṇa, reached Ayodhyā and was crowned is Dīpāvali. After the light of Rāma left Ayodhyā, Ayodhyā was filled with the darkness of Ajñāna. The whole forest was filled with radiance. Because Ayodhyā had been sunk in this sorrow, the people of that day, the moment Rāma entered Ayodhyā, saw Him as a divine light and in their joy celebrated this festival of lamps.
Root Out Ahaṅkāra
This day of Dīpāvali is the day Vāmana asked Emperor Bali to give Him three paces of ground as a gift and pressed him down into the nether world. This has another inner meaning. The sun has another name: Viṣṇu. They say the sun's chariot has seven horses. That is, the seven colours themselves are the seven horses. This chariot has a single wheel. This wheel has 360 spokes. They are the 360 days. This sun has three states: rising, midday and setting. Taking these three states as His three paces, He pressed down the Emperor Bali that is Ahaṅkāra. What does ‘emperor’ mean? It means the leader of all, one under whose sway everyone stands. In man, too, there is an ‘emperor’. All the remaining good qualities are under his sway. He is the “Emperor Ahaṅkāra”. That is why this ‘emperor’ called Ahaṅkāra keeps all the good qualities down. Another meaning of Ahaṅkāra is to mistake the body itself for “I”. The body is not you. This body is merely like a tool. It is merely a coming together of substances. Because a power of Caitanya has joined this inert body, it enters into every kind of action. So to take such a body to be ‘I’: that is Ahaṅkāra. The man filled with this Ahaṅkāra stays sunk in the darkness of Ajñāna. When this Ajñāna that is Ahaṅkāra goes, the radiant flame of divine Jñāna is lit. The day this Ahaṅkāra was pressed down is the day of Dīpāvali.
The Outer Light and the Inner Light
This day of Dīpāvali is the first day on which Emperor Vikrama ruled Bhārata. With many such things in view, the people of Bhārata, from boys to the old, have been enjoying this festival of Dīpāvali with great joy and delight. Yet these lamps drive away only the outer darkness. But they cannot in the least root out the inner darkness. Only the one “flame of Jñāna” can root out the inner darkness.
If we are to light a flame, we need an earthen lamp. We must pour oil into it. We must set a wick in it. To light the lamp we must also have a matchbox. So lamp, oil, wick, matchbox: only when these four are there can we light the flame. This flame drives away the outer darkness. As the wick burns, the oil too dwindles. By the time the oil runs out, the wick too stops burning. This is exactly what Rāmadāsu said:
“What is precious is the oil, friend! What is true is the wick, friend! When the light burns out, no one comes along, friend!”