This is the highest practice, which leads directly to spiritual immortality.
Via this method we realize emptiness and that "I am not", and therefore become Buddha.
After practicing for a certain time (3-4 months intensively) the spiritual embryo will crystallize.
What is turning the light around?
It is the process of inquiry which reverses the flow of energy, and attention from inside out, to outside in.
Here we are looking for the one which sees, hears, tastes, feels, smells and thinks.
Please consider fully the Theory of Relativity in respect to movement.
That which moves does so against that which is unmoved.
There is only movement relative to stillness.
Try with a pen against a desk. Either the pen is moving against the desk, or the desk is moving against the pen. It's all relative.
Therefore, movement doesn't exist of its own.
The universe doesn't move, as there is nothing for it to move against.
That which is inside the universe moves against other things inside the universe. Planets move against suns, solar systems move against other solar systems, etc.
In respect to practice, realize when we walk, or drive, either we are moving against everything, or everything moves against us. It is very simple and irrefutable but we need to fully comprehend this.
How to Practice:
Go for a walk or a drive and look at everything moving. Either we are moving against everything or everything is moving against us. If we consider us a person, we will say that we are moving against everything. Of course I am walking on the earth, or driving on the road.
But if we are moving, where are we moving to?
We can travel for a thousand miles by foot, and everything will look to be moving for the whole journey, and at the end of it we will be in the same place we have always been.
Ask whilst everything is moving am I still here, am I still here, am I still here?
We are always there in the same place we have been.
So ask again, is it me that is moving in the world, or is the world moving in me? If it is me moving, where am I moving to?
Remember, either we are moving or the world is moving. The Theory of Relativity is irrefutable, so we need to inquire.
In fact, we have never moved from where we are right now, and never will.
But everything moves inside us. We are still. That which doesn't move is immortal. The body is just another thing that moves inside, but it is also the vehicle that "makes us move", but actually makes everything else move. Even to say everything moves inside is not totally accurate because there is no inside or outside.
Practice this because through it we can realize non-duality which is experiencing emptiness.
Whenever we walk, watch everything move and consider self motionless.
Watch everything pass from our vision into the void behind. Carefully monitor the movement on our peripheral into the void.
We are not in the world, but the world is in us, even if we turn around we don't move, the world turns.
This is what non-existence or emptiness or nothingness means. Nothing exists in the world because there is no outer world. Because there is no outer world, there can be no inner world, hence Buddha is non-dual.
Keep practicing this, and a point will come where we will "meet our long lost father". This is the host, or the master. We as a person are the guest which has usurped the host. This is the delusion which becomes apparent at this point, and ceases. When we "meet our long lost father", we haven't seen him for a long time, but still we know it's him. Be careful here, as there is great joy in this meeting, and if we indulge in this joy, it will unsettle our energy, and the experience will be lost. In this event we will probably experience a sort of heartburn for up to a week. Once the heartburn goes, continue on with the practice. We won't have the sudden experience of "meeting our father" again, but will gradually develop and gain insight. If we avoid indulging in the joy, and heartburn experience, continuing practicing will be natural.
From here keep looking to see who is looking. Look at the world, but at the same time see if we can see the seer. Hear in the world, but try to see the hearer. Think, but try to see the thoughts. Taste, but watch the taster. Feel, but watch the feeler.
There come points when we make progress, then suddenly feel like pausing. Pause when this happens, and naturally after a day or so we will feel like turning the light around again. Then continue. This may happen a few times depending.
A point should be reached next when we begin hearing with our eyes. This is confirmation of our progress, so keep going. We are halfway-two thirds into our practice.
By this time we will be proficient in turning the light around. It is a knack which we have gained. So there is nothing to say but keep going all the time.
Towards the end of the practice we will need to turn the light around constantly. From the time we wake up until the time we sleep we will be turning the light around. No one will know what we are doing, or the progress we are making, and there is no point in talking about it. Try to act outwardly like everything is normal and we won't be disturbed.
Also when we are practicing, we get to the point where we notice when we are about to start thinking or drifting into imagination. When this happens use quick movements of the eyes. This fends off thoughts and imaginations. We just move them around as quickly and randomly as we can focusing for split seconds on different things at different ranges. Doing this ensures our practice doesn't get interrupted. If we practice this we will be able to pre-empt even the suggestion of a thought with a couple of eye movements.
At the end of this practice we will know. Initially there will be a tingling feeling on the top of your head, and our breath will change. This happens very suddenly and when it does we no longer need to turn the light around. Our practice is finished.
The breath will become like that of a child. Instead of breathing into our upper chest, or into our belly, we will be breathing with our diaphragm. Our rib cage will expand out to the sides, and our belly will suck in during inhalation and visa versa. This is just as a confirmation as we actually cannot change this breathing pattern once we get to this stage, unless we try to, which we won't.
The tingling on the top of our head is the sign to stop, but it will only be a slight sensation to begin with. Simply enjoy the sensation and watch it from a distance. If we try to do anything here we can overcook the process, so it is time to relax at last. This is what is known as "crystallization of the spiritual embryo"
Whilst enjoying the tingling feeling, we will notice it slowly expand over our head, face and down our whole body. It will take about a week for our body to be covered with this sensation.
We will also experience a ringing sound in our ears.
At this point we will feel great bliss. Enjoy this without indulging in it.
Now we wait for the spiritual embryo to develop. This will happen naturally, just like grass grows without interference.