There's a story that makes the rounds in the zen world in various forms, I'm sure it has happened several times, with several different people, so everyone has their own version of it, but it goes something generally like this:
A new meditator has an insight experience. I've had them too, they're pretty impressive, like a spiritual orgasm or something. It's what is commonly imagined that enlightenment may be, or nirvana, etc. etc. etc. It can take a myriad of forms, and it is truly beyond description with words, which is one of the things so wonderful about it. Quiet sitting has a way of reliably bringing these things on just like caressing certain body parts in certain ways will reliably bring on a sexual orgasm.
I had my first one as a young meditator, age 16, while being taught to meditate by one of the Catholic clergy at my Catholic high school. He was using a candle as the object of concentration, and I had the experience of merging my awareness with the flame, for lack of a better way to put it. I had another one during my first sesshin at San Francisco Zen Center, yet another while on a retreat in New Hampshire, and another one while riding the C Subway line in Manhattan (go figure). Like an orgasm, you know one when you have one. They are not subtle.
Anyway, I digress. The young (or new) meditator has this experience and then rushes off to their zen teacher to tell them about it, using carrying along some fantasy that the zen teacher is going to say "Wow! It usually takes years of dedicated practice to reach this level of deep understanding! I've never had such an advanced student!"
If they have a good teacher, the teacher will instead treat the experience as if it is a minor annoyance best quickly forgotten. Why? Because in the context of waking up to what your life truly is, that is exactly what these experiences are--distractions. They are wonderful, blissful, peaceful, comforting experiences, just as orgasms can be, but they have as much to do with zen practice as sexual orgasms have to do with getting your car washed.
My favorite version of this story involves a student telling (I think) Dainin Katagiri about one of these experiences. The student describes this wonderful powerful experience in great detail and Katagiri nods and says "Hmmm. How's your breathing? How's your posture?"
If you could speak to me about how things are going during a sesshin, you're not going to hear me tell you about the wonderful insight I've gained into Dogen, or Huang Po, or how I now see that all beings are unique manifestations of Buddha already perfectly enlightened. You're going to hear about my knees, my back, and about my suspicions that the person keeping time during zazen is sadistically messing with us by letting the sessions go longer than they are supposed to go.
Zazen, i.e., sitting motionless, is, at the very best, a mildly annoying experience. It can be painful and difficult. During this sesshin I primarily struggled during zazen with three painful and difficult problems. First, my left leg would go to sleep. This is somehow related to an interruption in regular blood flow caused by something to do with sitting motionless cross-legged. This is not a huge problem because it goes away within a few seconds after I uncross my legs, and I've learned to do this subtly on the cushion with minimal disturbance to those around me (there is an Art to that).
The only problem with this is that zazen is essentially a yoga posture, like the downward dog or something, and if my legs are uncrossed I'm not sitting zazen. So, for whatever period of time that I rock back and swing my foot in front of me to resolve the problem is time I'm not doing zazen. Well, I'm sitting there to do zazen, so this time that I sit in a different posture in order to get the feeling back in my leg is "wasted" (for lack of a better term). No matter how much I try to retain my mental posture, this isn't zazen. It is not what I sat down to do.
My second problem, in order of the amount of distress it produced, was the pain involved with stretching out my quadriceps, the muscles on the front of my legs, because my knees are folded in, flexed almost as far as they can go. It hurts, particularly early. It's a sharp constant pain streaking down the muscles, and this merges with a very similar sensation in my knees also related to stretching tissues in that area. It's not excruciating pain, but it is significant. Many times at the end of a zazen period I would grab my thigh as I unfolded my leg and silently shout "Motherfucker!" to myself as I unfolded it. Something about this private, silent, screamed vulgarity helped, I'm not sure why.
My third problem, and by far the most distressing, was a dull ache in the middle of my back in the mid-thoracic region, roughly a few inches below the area between my shoulder blades. What was most annoying about it was not the intensity of the pain, I'd rate it about a four on a scale of one to ten, certainly tolerable. The worst part was this notion that if I could just lean back on something it would completely go away.
Imagine leaning against a steam pipe that was not hot enough to burn your skin but far too hot to be comfortable. All you need to do to rid yourself of this discomfort is stop leaning on the pipe, yet you are committed to leaning against this pipe for some reason that you don't really understand. After a while this fact--that you're doing something to make yourself uncomfortable that you can immediately relieve--causes all sorts of mental distress. This struggle with "why the hell do I do this to myself?" is actually worse than the pain.
I went for Dokusan, a private interview with the teacher, at my very first opportunity to discuss this problem. He has been sitting zazen for 40 years, certainly he knows about this, and he did. I described what was going on and he said "Is it a vertical pain or a horizontal pain?"
"Horizontal, a band across my back, below my shoulder blades, a dull ache." I said, leaning forward in anticipation of his wise counsel and immediate solution.
"Oh, if it is not vertical than this is something you're probably going to have to just put up with during the rest of this sesshin. You do slump some and round your shoulders, it probably has something to do with that" he said, probably knowing that wasn't the answer I wanted.
Great. It's like the old joke about going to the doctor and saying it hurts to do this and he tells you to stop doing that. I knew this was about slumping, because exaggerating my slump made it go away. Thanks, great Master of Zen, very helpful. What I wanted him to tell me was some minor adjustment to make in my zazen posture that would magically resolve all this. No dice.
So, I could exaggerate my slump, probably looking a bit like I was suddenly horribly depressed about something (not too far from the truth from time to time as I struggled with this, to be honest), but that's like swinging my foot in front of me to remedy my leg going to sleep. Slumping is not zazen. It is impossible to maintain the proper mental posture when you are not in the proper physical posture. Slumped time on the cushion is also wasted time on the cushion.
After three days of this the pain began to persist even off the cushion. My back hurt. My muscles were aching. I wanted a massage, preferably by a bikini-clad Japanese woman named something like Miyuki, but I would have accepted one from a bald guy named Fred who was clad in an dingy white t-shirt and grey sweat pants. It hurt.
I thought I had an insight. I'll just take some Ibuprofen! I had none with me, but there was a first aid kit in the zendo so I raided it. No Ibuprofen, but there was aspirin, so I took ten grains. This resolved the pain off the cushion, my back didn't hurt all the time any more, but it did very little for my experience during zazen.
Sesshin practice is different than daily practice. I sit zazen every day, at least twice, once in the morning and once in the evening. I sit for twenty minutes, and I experience some minor version of every sensation I had during sesshin in my daily practice too, but only for a few minutes twice a day. This is like the mild discomfort associated with working out, or climbing stairs, or shaving. You forget about it. It's no big deal, you put up with something for a minute or two and then you go on with your day.
In sesshin it goes on all freaking day, or that's what I'm thinking anyway.
Now, the truth is there is no "all day." There is only this present moment. Ever. There is no other time. The notion that a pain experienced for ten seconds is something worse than the same pain experienced for 6 hours (the amount of daily zazen done in these sesshins I attend) is just a story we tell ourselves. A pain is a pain. It either exists or it doesn't, right now. We make pain "worse" with these thoughts that linear time exists in the way that we conceive of it, but that's really another discussion for a different essay.
However, you can create another kind of pain, the pain that persists off the cushion, from extended periods of time straining your muscles like this. This is actually minor injury, a muscle strain, and I could eventually feel the swelling in this area of my back. I was "injured."
At the end of day three and four I literally almost ran to bed so I could lay down flat. It didn't hurt that way. At the end of day three I was so exhausted by working with this soreness that I fell into a deep sleep almost immediately after getting into bed (and was visited by a bikini-clad Japanese woman named Miyuki while dreaming, but that's yet another story). By day four I had some additional insight into my mental contributions to these physical problems so I wasn't so exhausted by them, but my back still hurt. I could still feel the swelling.
I'll discuss more about this in the essay "Great Sincerity." My struggle here was emblematic of what I will discuss there, but I do want to round-out this story about straightening-out my back. I did fix the problem. I did figure out what I was doing to make my back hurt.
When I sit, even as I sit right now typing this, I typically lean in my chair against the very same area of my back that was causing me all the trouble. My lower back is generally not touching the chair below it, and I bend forward a bit in order to make my upper back vertical so I am not gazing up at the ceiling while trying to type. It is a bad habit, I'm not recommending this posture, but it is what I do.
Extended periods of sitting this way, years really, has caused my muscles to orient in such a way to make this position comfortable for me (otherwise I would sit in some other position, duh). This is not zazen posture. When I orient to zazen posture, my muscles are not doing what they are used to doing, so they aren't strong in the ways and areas needed to sit comfortably with my thoracic spine perfectly straight, and they complain about it.
My zazen posture was subtly off. I wasn't maintaining enough of a curve in my lumbar region. When I made this adjustment (the internal experience is that of sticking out my butt in back and rounding out my belly in front) the pain faded. Fortunately, I did finally figure it out and zazen stopped being painful. Zazen finally fulfilled it's promise: it was only mildly annoying.
Unfortunately, I figured this out during the third-to-last sit on the last day. That is, out of 60 zazen periods I sat over five days, numbers 58, 59 and 60 were only mildly annoying. The rest were frankly painful, in varying degrees of intensity.
Sits in the morning were easier, and the first of a set of three sits was easier than the second and third. It was all very ordinary in this sense: exactly what you would expect, exactly like the soreness from doing anything physical (which causes soreness, yes, even that) that you aren't used to doing every day (no, I'm not, and that's Miyuki's fault). The more I did it the more sore I became. It got better over breaks, but less better over the course of a day.
It even started to annoy me during kinhin, walking meditation. At one point I was so tired of it that I moved to a chair to sit, but by the time even sitting in a chair didn't help. That was very discouraging, but that's yet another story.
So, this is what sesshin is like during sesshin. You aren't wandering between these experiences of being one with the universe, or running off to tell your teacher that you have figured out the sound of one hand clapping, or that you now know if a tree falls in a forest and no one hears it whether there is a sound. No, you're dealing with your body. You're dealing with what shows up. This is zen practice. It's not very sexy (unless Miyuki is around), but this is the path to liberation. I know that.
Quiet naturally, you might wonder if this is all worth it. Yes, it is. What's at stake here is nothing short of personal liberation for all sentient beings. Caring for my back during zazen is no different than caring for the entire world. If you want to understand that, well, there's a method, but you might get a little sore along the way.