In light of the books on the jhanas, with descriptions of the immaterial jhanas, and so on, I do believe these are not foreign to us yogis’ perceptions doing our usual daily meditative sadhanas.
The eighth immaterial jhana is an at-first-startling culmination of meditative practice, where the perception of separate ego identity drops away, as the thought stream ceases, and also any sense of the physical body, and there is just awareness of light globally. And when leaving this level, there is resumption of thought and of time and body awarenesses.
I’m sure others here could corroborate this.
Nevertheless, the kasina meditation practices of visualization should be a useful project, don’t you think to recruit the visual cortex into this fully?. That’s my take. I really appreciate being able to run this by you folks. Thanks for your feedback in advance.
Hi John,
Although I’ve never practiced the kasinas, the method seems pretty straigt forward. It is, as you say, a form of tratak, so it is used for developing concentration and samadhi. It would have the advantage over breath meditation, that the object is not lost once awareness of the body is lost.
But breath meditation can also be used for entering jhanic absorbtion, along with some practice such as the four foundations to overcome the problem of the loss of the breath in deep samadhi. Deep Meditation can also be used of course, which, incidentally is also a form of tratak, and also has the advantage that the object of meditation is not lost when bodily awareness is lost.
Lots of choices. 
Christi
John C, I also found out this exercise, by chance, and I’m convinced it purifies the visual cortex: go out on a sunny day, on a late afternoon or early morning, when the sun isn’t too strong; look directly at the sun with the eyelids closed for a minute or two; there should be some light, and it should increase as you do this; the look away, still with the eyes closed, maybe cover your eyes with your palms, and let it settle into darkness. Repeat a few times, or not, as it suits you. Now open your eyes.
That’s the exercise. When I do it, it seems to stimulate the visual cortex, and the quality of visual experience will be very refined. I’m guessing that with repeated long-term practice it would lead to some serious change, but I have only done the exercise sporadically. During the settling phase, there are all sort of weird visual sparks and stuff going on.
brunoloff,
I think you are playing around with the famed Purkinje hallucination
I find this thread very interesting.
I thought I would just notify you that some people claim visualisation can never get you as deep as focusing on energy itself or a sensation by itself. I have seen this discussion only with regards to energy practices were energy is moved were it is discussed wether to use visualisation or just intent so it might be different than a frozen visualisation. I have no clue about any of this but have experiemented a little bit with trying to shut of imagery all thogther, just focusing away from whatever mental imagery I have and this apears to take me much deeper much quicker.
@alwayson2: Not really, I don’t experience any moving images while I do it. After reading about these hallucinations (interesting stuff!), there is a considerable difference with the exercise I’ve mentioned: One does not flicker the light on and off, one stays with the sunlight behind the eyelids for a minute or two, then rest for a minute or two. It’s a bit as if the sunlight was massaging the visual cortex.