What is a cosmic experience?

When people have the experience of cosmic consciousness they are surrounded by a bright light. How do you account for this?

Cosmic consciousness is simply the soul's eye being opened and seeing spiritual light, which is a strong, intense and vivid reality hence the illumination of the soul's environment and thought.

Very few have it. Can it be cultivated?

Very many have it, but not written about.

Then is it the natural experience of a spiritual nature?

As natural as the life, of which it is an attribute.