Nirvikalpa samadhi is another matter. In order to enter into nirvikalpa samadhi, you must have a great deal of humility.
Salvakalpa samadhi is like a sea of perfect light; nirvikalpa samadhi is no light, no darkness, no way to describe it. Absorption is complete, that's nirvana.
When you eneter into samadhi and seek to make that magical walk between salvikalpa and nirvikalpa samadhi, it's necessary to focus your awareness not on being or nonbeing.
Salvakalpa samadhi is absorption in eternity to the point where there is no real concept of self but there's still a karmic chain. Nirvikalpa samadhi is absorption in nirvana; concepts of self and no-self go away completely.
There is such a thing as everyday, ordinary, vulgar ecstasy; the ecstasy of anger, the ecstasy of speed at the wheel, the ecstasy of ear-splitting noise, ecstasy in the soccer stadium.
Begin with dhyana, with meditation, and end in samadhi, in ecstasy, and you will know what God is. It is not a hypothesis, it is an experience. You have to LIVE it - that is the only way to know it.
The whole art of ecstasy, meditation, samadhi, is: How to become one with the rhythm of the universe. When it exhales, you exhale. When it inhales, you inhale. You live in it, are not separate, are one with it.
Nirvikalpa Samadhi means you are sitting in meditation and you go beyond the planes of light to nirvana. Then you come back and here you are "back in the saddle again".
Nirvikalpa samadhi is a state of no mind, beyond the ten thousand states of mind, where there is nothing but perfection, where the self no longer exists...the ego dissolves into immortality.
Nirvikalpa samadhi is another matter. I don't feel that's really up to us. That happens at a certain time when our being has gone through countless changes and refinements.
When you go into samadhi, either salvikalpa or nirvikalpa, what happens is you erase, you loosen, the aggregates. You simplify them.
The light of the supra-conscious, of salvakalpa and nirvikalpa samadhi, is not connected to this world at all. It passes through this world but it is not part of this world, in a way of speaking.
Even in intake, the one steadfast thought is said to be the natural state. Nirvikalpa Samadhi will result when the sensory objects are not present.
Who is that is dreaming all of this? Ecstasy, pure ecstasy, joy beyond understanding, bliss beyond the dry dullness of the mind's philosophical ranging, light beyond any light in this world - The substance and the essence of all existence is this light, the transcendental light.
Eventually you will go into samadhi. Samadhi is a very advanced meditation. You dissolve into the clear light of eternity again and again.
The higher octave light that comes from samadhi, the kundalini of samadhi, this you can absorb continuously. You can never overload. It can never hurt you.