What is it?
This topic is usually a core Idea of tantra. Why teaching here? Because of experiences.
The essence of experiences is nadh.
What is nadh?
It is simply change. What kind of change? No kind of change.... simply a change.
Because of change we are able to experience many things. Example - if you experience a dark room but if there is no nadh simply means if there is no change then shifting or experiencing other light room is just impossible. This is just example you can clearly see this nadh in your own experience. Nadh cannot be seen just like gravity but you can see it like you see gravity, in simple you can see nadh effect.
Tantra is study of illusion. They call it there energy not illusion but we like to call it illusion.
See i myself is not a practitioner of tantra. I only know basic of it. This answer is given because it helps us to understand the essence of experiences itself.
Just we can conclude the essence of Consciousness as experincer which is formless similarly nadh is the smallest understandable form of or you can call it essence of experiences. We cannot go smaller than this. The smaller than this is state of nothingness.
Now you are able to connect dots right? Because when I say that both the experiencer and experiences are me this is what I generally means. Because both comes from zero state. Experiencer is non changing and nadh is changing. This is why we call nadh illusion because if truth changes then it won't be a truth, and experincer is ultimate truth from perspective of non - changing because experincer is immortal this is your soul.
Oneness is simply how exsistence is exsisting....... Both comes from zero state so both me. Enlightenment is nothing but to know a simple fact that I am exsistence and without experiences a experincer cannot exsist or vice versa.
Now you can do one thing to make sure that all of this is not fake.
See it in your own experience. Isn't the smallest part of experiences is change itself? If no change then no experience can exsist. This much you can see right? And you can then also see this fact that we cannot go smaller than this because that would also be same concept. Example - if you find out something other which is smaller than nadh then doesn't that knowledge itself come from change? So it is not possible to find smaller than nadh.
Similarly you can see that it is not possible to find smaller than experincer in terms of Consciousness. If you can find other experiencer then ask who is the experiencer of that? Nobody right? Experiencer cannot experience itself because then who will experience it?
I provide this knowledge because all the illusion or you can say energy in terms of tantra work on one basic concept that is simply change if you understand this you understand basic core idea of any form of experiences or energy. See how experiences comes from nadh i.e.
Because change can happen infinity times there is no time or not end of it that is why even a simply nadh even a simple vibration of line could possibly create variety of different experiences.
The depth of this topic don't come under my knowledge. I have knowledge of basic tantra. This is much I can tell only.
Now this knowledge is given to you because so you can use it to know oneness not to use it for some kind of crazy experiments given in tantra. Our goal is oneness not tantra.