In Indian Culture: Why do we light a lamp?

Every night, almost without fail, my grandmother insists upon lighting a small oil or ghee (purified butter) lamp in front of our small altar of the Lord. We allow it to burn through the little cotton ball wick and never blow it out manually. Some houses, I've heard, even maintain the light of the lamp continuously--never letting it go out.

All auspicious moments such as daily worship, festivals, and rituals are begun with the lighting of a lamp, which is kept on throughout the occasion.

So, why do we light the lamp?

Light symbolizes Knowledge, knowledge that dispels Darkness, which symbolizes Ignorance.

The Lord himself is considered the "Knowledge Principle"; thus as He is the source of all knowledge and life, Light is worshiped as the Lord himself.

Knowledge that we internalize helps us achieve greatness and is a wealth beyond paper money. Therefore, upon lighting a lamp, we bow down and give respect to the greatest form of wealth. Our thoughts and actions have a foundation in some sort of Knowledge (or lack thereof) and thus we light the lamp during auspicious occasions to keep witness to those thoughts and actions.

Now, if Light is so significant, why not just turn on the light-bulb or tube-light? That'll remove darkness too right?

By doing that, we removed the significant spiritual symbolism of a traditional oil lamp. As the Oil or Ghee in the lamp represent Vasanas (A good definition is in the post Bhagavad Geeta: An Introduction) while the wick represents the ego. As we ignite the wick with the light; knowledge burns away the vasanas and the ego as well.

While the oil and wick go down, the fire always burns upward; in this way we should use knowledge to take ourselves to higher ideals.

A single lamp can light hundreds of others, just as a single realized master can enlighten thousands. Despite sharing its light to other lamps, the original lamp loses none of its brilliance. In the same way, sharing knowledge will not result in the loss of that knowledge; on the contrary, upon giving knowledge, we begin to understand it clearer and it benefits all.

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