None. Not just "none that I would be willing to talk about in public", but no "spiritual" experiences at all.

The scare quotes are because I do not know what people are intending to point to when they use the expression, or elaborate upon it. Whatever they are pointing to within themselves, when I take hold of the words that they use, they do not point to anything within me.

The closest experience that comes to mind was in an undergraduate tutoring session for a first-year mathematics module, where "just for fun" at the end of the session we were taken along a path of derivations from the subject matter we'd just covered, up into some more abstract math, and then back down into something more concrete and familiar that had (until that point) always seemed like an entirely separate area of mathematics.

For a brief moment it was like everything fell into place, and I was face to face with the infinite / eternal / perfect structure of the universe. But then the session ended and the spell broke, and I realised I couldn't quite remember it all well enough to recreate what had just happened.

But there's no experience I can report that ever made me suspect the involvement of the supernatural or the divine.

In the late-80s I was interested in Buddhism and Vipassana meditation. I attended several 10-day silent mediation retreats at the Insight Meditation Society in Barre, MA. These were all over New Year's. They were pretty profound, and after three of them (1987, 1988, 1989) I decided to do the three-month silent retreat, which ran every year from about mid-September through mid-December.

I was in the Navy at the time -- with 12 1/2 years already in -- but I got out and attended the three-month retreat in the autumn of 1990.

It was three months of mostly silent sitting on a meditation mat in a big hall with about 100 other people, or performing walking meditation. The days tended to be punctuated with an hour of sitting, followed by an hour of walking, followed by an hour of sitting, etc.

Of course there were meals -- breakfast, lunch, and an afternoon tea with rice cakes -- and there was an evening dharma talk in the meditation hall (rotated among the four retreat leaders). Also, to make sure people weren't going batshit insane, there were once or twice weekly individual meetings with a retreat leader.

During the three months there was no talking among retreat attendees, no eye contact, no music, no television, no nothing. Just you and your feeble attempts to follow your breathing for more than four or five breaths without having your mind wander off into some fantasy.

Prior to this I had been a Navy SEAL. In going through Basic Underwater Demolition/SEAL (BUD/S) training, I was looking for an experience that would reduce my existence to just consciousness and the will to go on. For some reason I thought BUD/S -- with the fabled five sleepless days of Hell Week -- would produce something along those lines. It didn't. BUD/S was actually pretty disappointing from that point of view. You just had to not quit.

I did find what I was looking for on the meditation mat, though. About a month into the retreat, in the absence of any of the normal distractions and stimuli that allow us to form opinions, etc., the mind does strange things. It starts to crack a little. Or at least it did for me. You can't even begin to imagine the waking heavens and hells that start unfolding inside your skull. At times I just wanted to curl up in a ball and cry.

And eventually a space began to appear. I began to become aware of a little separation between the movies that were playing in my mind and the observing entity that was aware of them (and not attached to them). For lack of a better term I'll call that entity my consciousness.

It was very much like the beginning of the Woody Allen movie, "Play It Again, Sam" where Woody Allen is watching "Casablanca" and totally identifying with the movie. Then the movie ends and the lights inside the theater come on, and you can see Woody Allen become aware that he is not the move, he was just watching the movie.

For me that's what Vipassana mediation was about: realizing that you have no control of your mind. Your mind will produce ideas and emotions and fantasies and any number of things completely on its own, similar to how your liver will produce enzymes on its own. But there is also an observer that can detach and not identify with what the mind is doing. That observer can dispassionately watch what's playing on the screen, and not get all caught up in it. The observer can watch it...label it...and not act on it. The observer can just let it float on by. That was serenity.

I met the woman who became my wife at one of those retreats. (She has done two of those three-month affairs). Although we've both moved on to different phases of our lives, somewhere not far from our daily thoughts is the notion that someday we'll move back to central Massachusetts and spend more time of the meditation mats before we die.

Almost half a century ago, when I was 16 or 17 and still believed in God, I went to a synagogue with some people of my church for some kind of exchange thing. The service was quite boring though, as everything was in Hebrew and I didn't understand a thing. But there was nothing to be done except sitting still trying to be respectful. So I guess I fell into some kind of meditative state, and I don't remember anything about that, but just afterwards I felt that I had been in the presence of God, and a sense of great gratitude. I'm still surprised I didn't convert to Judaism on the spot; maybe I would have if I weren't so shy...

Now that there are a couple other answers, I'll talk about one of my own, keeping in mind I now think of the kind of thing I'm going to describe as a part of my typical field of awareness that I can choose to pay attention to or not.

Once during sesshin (an multi-day period of dedicated practice in zen focused on meditation, literally a gathering of mind), after a particular rough morning where I was very restless and was expending a lot of effort just to stay on the cushion, my teacher gave a talk on the teaching poem "Trust In Mind". We had lunch, a one hour break period, then returned for afternoon meditation period around 1500. My body hurt, so I swallowed my pride and sat in a chair rather than on a cushion on the floor, the first time I had ever done that in the zendo.

Between surrendering to the pain in my body, my pride, and my teacher's encouragement to trust, I suddenly found myself giving everything over. My big notion of self fell away and my awareness opened in a deep way that is hard to put in words. This had happened to me before, but only in little flashes. This time it persisted, lasting for hours, giving me the opportunity to be with and explore my experience.

Eventually I "forgot" how to remain in that state and my big sense of self returned a few days later after the sesshin ended and I got tangled up in my "regular" life, but I was transformed in some subtle ways by the experience such that I now had a trust in the world to be just as it is in a way I didn't before.

I can think of three types of experiences I've had over my life that might be described as spiritual or mystical.

One long ago, and certainly drug related (grew up in the late 60s and 70s). The experience was essentially an "out of body" experience. I was floating in space, somewhere like the orbit of Saturn or Jupiter. I was being told, if I wanted it I would be given absolute power on earth -- I would have everything I wanted. My response was No. I did not want that type of power. I only wanted control and power over myself and my decisions. Make was you will about the "vision" and the whole temptation theme but that was really when I realized who I wanted to be at a fundamental level and what type or relationship I wanted with the rest of the world. I wanted to be me and to let others be themselves.

In general I have been rather lucky. I have been quite a few situations were things could have gone really poorly for me, like not being alive. I've never been seriously hurt. After one of the accidents I was several people kept asking my how I was not hurt or dead after seeing the car I was in. I have frequently had the feeling that something is watching over me. I can accept that as just lucky, in instinctive in terms on understanding dynamic forces so just know to position myself in a good orientation to deflect more than absorb the shocks.

Lastly, now and then when I'm thinking about "big thoughts" like meaning of life, is there something more like some god and what exactly that might be (I don't buy into the formal conception of god that Christians, Jews or Muslims seem to have ) I sometimes feels I've touched on something and get sensation that is like s an energy passing through me or that perhaps I am passing through some energy barrier. It's a bit hard to explain but clearly could simply be some neurological sensation (What was that line from A Christmas Carol, "You might be nothing but a piece of the lamb chop I ate for dinner." -- probably not accurate) However, I really cannot say I find such an explanation any more convincing. I'm comfortable living with things like this unexplained for now.

Earlier this year I read Mastering the Core Teachings of the Buddha, which for the first time gave me a useful vocabulary for experiences I had already had. I describe the experiences, and then the names I'm mapping them onto.

My freshman year of college I was walking back from a class, really focused on some aspect of the material, when all of a sudden I started making lots of concept associations quickly, and it felt like everything I knew was assembling itself into one big tapestry, full of colors and patterns. Not a hallucination - even then I didn't think I literally saw anything unreal - but during and after it did feel like the world around me was more full of color than usual, for a while. Euphoria, which lasted for the next day or so. Didn't actually "learn" anything from it in the traditional sense. Maps to: Arising and Passing Away.

A year later I was at an Aikido class, staring intently at a demonstration, and my vision narrowed to a very tight spot, everything else blurring out. Maps to: first jhana.

From 2016 to 2018 I was going through clinical depression, and started meditating much more regularly. My depression manifested in part as a lack of emotion, motivation, and action, which made it artificially easy to quiet my mind and focus inward. Meditation was generally accompanied by strong feelings of peace, but nothing spiritual, Then I started antidepressants, and was very lucky in finding one that worked for me really quickly. My meditation practice changed dramatically a few weeks later. I became very aware of individual pulses of sensation throughout my body ("vibrations") in vision, touch, and temperature. I felt increased separation from my own sense experiences, like I was watching them instead of being them.

I reached stream entry along the way shortly thereafter- there was a moment of having no experience at all. It was odd and unmistakeable. Then, for about two weeks, a single focused breath would bring up waves of bliss, and make my whole field of vision sharper and brighter. Maps to: second or sometimes fourth jhana.

Since then (it has been 9 months) I've noticed sustained changes in how I perceive the world around me. It's like I'm seeing more of the raw sensory data, or can more often see through the model my brain builds for conscious awareness. For example, walls and tiles patters are more...swirly away from focal vision, and sometimes when reading text my eyes will unfocus or focus less without impacting the reading process much. When I look at a picture, it may go from normal to completely 2D or super-3D, and the same has happened when watching a TV from a wide viewing angle. A few times a week I'll be walking and all of a sudden my surroundings snap into focus (visual, tactile, and auditory) much more than normal.

I don't assign any mystical meaning to these experiences, but they have really changed what my algorithm feels like from the inside.

Thanks for this.

I don't have good descriptors for them presently, so I'll just note that I've had some spiritual experiences. They have tended to be very helpful for my everyday life. A few of them included powerful synchronicities.