At the time when oil lamps were used for lighting, the glass tube had to be cleaned often to remove the build-up of smoke. Otherwise, even if the wick was lit, the lamp would not provide enough light.
Fortunately, we now have electricity.
Why am I talking to you about oil lamps? Because human beings are like lamps.
If they feed their flame with oil, that is to say if they give in to coarse, vulgar feelings, these are deposited as smoke or soot in their astral body, and the light inside them – the rays of their higher self – cannot cut through this opaque layer. They therefore remain in darkness, blind to the divine world, until the day they learn to burn better fuels: feelings that emit no impurities.
If initiates and the wise see things that others cannot see, it is because they have worked long and hard to make their psychic matter transparent: a whole subtle world is made visible to them by their higher self whose rays are far-reaching.