"Well, there's zazen and zazen.
Out of interest, there's a rather excellent book on Zazen, one of the few actually worthwhile books on the subject, IMHO, called Zen Training, by Katsuki Sekida. It's totally congruent with the way AC describes meditation."
I think there are probably many good books about Zen or zazen. But one of the things I like about my zazen is that it doesn't require many books, just the simple techniques such as counting breath, following breath and shikantaza. It has many of the same things that Crowley described in Mysticism and other places. For instance, new practitioners of zazen start by sitting still cross-legged and counting breath in a relaxed and focused manner, keeping the mind in lower belly. Maybe it's just a preference, but I found it useful not to think 'now I'm mastering asana and now I'm mastering holding a cup of water on my head, now I'm mastering dharana, now I'm mastering dhyana', etc. I've been practicing just following my breath for years now. Other thing I didn't so much learn from Crowley is the emphasis of kind of a slightly passive yet focused and relaxed state of mind and body. For instance, Crowley maybe suggested things such as focusing on a mantra so strongly that other thoughts will be splintered away. I found the approach of kind of passively letting the thoughts come, observe them and let them go away instead of forcing it more beneficial for me. One more thing I personally found useful is to simply consider even fancy seeming experiences just makyos and continuing with the practice, such as following the breath.
"The problem is this: "insight" in itself is fairly easy to get - one can have flashes of satori or non-dual realization in all sorts of situations. And for most people that's enough, just to have that flash of insight, it helps put life in perspective.
But it's pretty fugitive, and useless in terms of giving you something solid in life, or in terms of enabling you to teach others (and the A:.A:. is all about teaching), without a parallel training in "calming" meditation. (The equivalent in Theravada would be that you have to pursue the Jhanas to a certain extent in order to be able to meditate on the Four Noble Truths properly.) The insight has to be "fixed" by a good grounding in (initially) rather boring calming meditation and the occasional deep bath in nescience.
Now the real gem in Sekida's book is that he points out there's a certain stage before which you haven't really gotten your foot in the door of that kind of meditation yet, and that stage is absolutely parallel to what Crowley calls "Asana" - no signals from the body. And there's no getting around it - it's quite difficult and painful to get to that stage.
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One of the reasons I like zazen is that it at least somewhat de-empathizes different stages, attainments, etc. Currently I value the benefits of zazen in being more relaxed, focused, etc, in everyday life and I'm not trying to reach dhyana and satori, etc. In a sense, I now view even zazen an advanced kind of practice. For many people, it would be much more efficient to first get their body and nutrition in condition, maybe exercise, hiking, martial arts, chi kung, whatever, and only then start with more rigorous and advanced meditation practices.
In any case, thanks for the Sekida reference, I'll put it on my books to read list.