I’m not entirely sure why Japanese Zen split into the soto and rinzai sects. Auckland Zen Centre practises Integral Zen, which I don’t really know a lot about, but it’s an interesting thought.
And then there’s the thought of meditation stages:- counting the breath, focusing on the single breath, and I guess focusing on nothing. If I’m to understand the practise of silent illumination properly, this last one is that. Patanjali describes I find focusing on nothing requires a level of concentration that the others I guess are indeed a preparation for. Perhaps this is why people like Gil Fronsdal and Bhante Henepola Gunaratana describe Zen as the most difficult practise.
Huatou practise (wato in Japanese, but more commonly and less correctly known as koan practise does indeed seem much easier. Personally, I like to do that as well. As I wrote in an earlier post, my question is “what is emptiness?”. And these to practises seem to dovetail quite well, but I practise focusing on nothing first. One of the reasons is that while huatou is meant to cut thinking off at the root, the mind occasionally finds things to grip on to. Another reason is that it seems to deepen the sense of emptiness observed in silent illumination practise. Patanjali refers to meditation with seed in Book I, 46 of his Yoga Sutras. And meditation without seed in Book 3, 8.
I think I’ve talked about the first two rules of magic before. The Tibetan as I recall it anyway observed that the personality and soul need to be meditating in alignment. Technical discussions aside, I think the practise of silent illumination is in one aspect the personality actively listening for what Blavatsky calls The Voice of the Silence. And this I think the practise of silent illumination does more readily.
And then both practises are the same. By the way, I think Sheng Yen’s book on this topic The Method of No-Method: The Chan Practice of Silent Illumination is a good one; a good addition to your meditation library.