Various kinds of lights manifest during meditation owing to concentration. In the beginning, a bright, white light, the size of a pin’s point will appear in the forehead in Trikuti which corresponds tentatively to the Ajna Chakra of the astral body. When the eyes are closed, you will notice different colored lights such as white, yellow, red, smoky, blue, green, mixed color, flashes like lightning, like fire, burning charcoal, fire-flies, the moon, the sun and stars. These lights appear in the mental space, Chidakasha. These are all Tanmatric lights.
Each Tanmatra has its own specific color. Prithvi (earth) Tanmatra has a yellow light; Apas (water) Tanmatra has a white light; Agni (fire) Tanmatra has a red light; Vayu (air) Tanmatra has a smoky light; and Akasha (ether) Tanmatra has a blue light. Yellow and white lights are very commonly seen. Red and blue lights are rarely noticeable. Frequently there is a combination of white and yellow lights. In the beginning, small balls of white light float about before your eyes. When you first observe this, be assured that the mind is be coming more steady and that you are progressing in concentration. After some months the size of the light will increase and you will see a full blaze of white light, bigger than the sun.
In the beginning these lights are not steady. They come and disappear immediately. They flash out from above the forehead and from the sides. They cause peculiar sensations of extreme joy and happiness and there is an intense desire for a vision of these lights. When you have steady and systematic practice for two or three hours of meditation at a stretch, these lights appear more frequently and remain steadily for a long time. The vision of the lights is a great encouragement in sadhana. It impels you to stick steadily to meditation. It gives you strong faith in superphysical matters. The appearance of the light denotes that you are transcending the physical consciousness. You are in a semiconscious state when the light appears. You are between the two planes. You must not shake the body when these lights manifest. You must be perfectly steady in the Asana. You must breathe very, very slowly.
One whose food is moderate, whose anger has been controlled, who has given up all love for society, who has subdued his passions, who has overcome all pairs of opposites (Dvandvas) and who has given up his egoism, gets a vision of a triangular light during meditation.
Sometimes during meditation you will see a brilliant dazzling light. You will find it difficult to gaze at this light. You will be compelled to withdraw your mental vision of this light. This dazzling light is the light emanating from the Sushumna.
You will see forms in the lights – either the lustrous forms of demigods (Devatas) or physical forms. You will se your Ishta Devata or chosen deity in handsome dress with four hands and weapons. Siddhas, Rishis and other Devatas appear before you to encourage you. You will find a huge collection of Devatas and celestial ladies (Apsaras) with various musical instruments in their hands. You will also see beautiful flower gardens, fine palatial buildings, rivers, mountains, golden temples, sceneries so lovely and picturesque as cannot be adequately described.
The experiences vary with different individuals. What one man experiences, may not be experienced by another man. Many erroneously believe that they have realized the self when they get these experiences, stop their Sadhana and try to move in the society to preach a new cult and religion in the name of Loka-sangraha. This is a serious blunder. This is not realization at all. These are simple encouragements from your Ishta Devata to convince you of a higher spiritual life and push you on in your steady, systematic and incessant practice of meditation with zeal and enthusiasm. You will have to ignore these things and drive them away. You must not care a bit for the vision of lights. You must fix your attention on the Lakshya, the goal, viz., Brahman. These visions appear in some persons within a few days, while in others within six or nine months. It depends upon the state of the mind and degree of concentration.