It is relatively common for people early on the path to have a BIG experience. It doesn't have to play out that way, but again, a big initial awakening or opening is not exactly a rare event. What's going on? What is that about?
The experience referred to here often has some kind of taste of complete freedom or liberation, possibly great joy, love, light, etc. In the Theravada progress of insight, this kind of thing falls under the technical mapping as the stage of knowledge of arising and passing. It may happen as a result of meditation, most commonly on an early retreat of some kind, or from using a psychedelic. Extremely rare individuals may stumble in by simply reading a sentence that gives them great insight.
The experience may be so big that a person may think they are enlightened. Indeed, they may have gotten a glimpse. But as pure as that experience can be, it would generally be somewhat tainted by being viewed from substantially within the assumptions they currently hold.
To my way of thinking a couple of things are going on here. On the one hand, in order to have a big experience, you need a thorough indoctrination into attachment to language, concepts, beliefs, cultural assumptions, and identity. Check. Pretty much all people fall into this category. But the more attachment the better. My speculation is that it could "help" if the person is particularly rigid about some of these things, solidly married to their worldview, even neurotic about it.
The other side of the coin is that you then need a complete relaxation of all these things. You need to stumble into a pure consciousness that has dropped as many of these attachments and rigidities as possible. A complete letting go into pure consciousness, the metaphorical original mind or natural mind. Complete freedom. A thoroughly different point of view.
It is the difference between these two that creates the ground for a big experience. The more radical the change in perspective, the bigger the relief, the more dramatic it will be perceived. For some people who already "get it", it might not be as big, it might not ever happen that way. This would be like someone who has been meditating a little bit over time and slowly gets it, kind of like the apocryphal metaphor of boiling a frog. But for someone who is more thoroughly entranced by thought addicted identity views, the bigger the experience might be. And again, pretty much everyone is subtantially "attached", even if they've read a whole stack of buddhist books.
The blue line in the graph above attempts to portray the theoretical progress over time of a typical person on the path. Slow at first, then perhaps a tipping point such as stream entry, and a resulting acceleration, and then a slowing down again as one asymptotically approaches some ideal. Actual progress could be much noisier and more different.
The graph explains why the big experience is generally only possible early on, or in the acceleration phase: the gulf that creates the ground for the experience is vast at first, but as progress is made, the chances of a big, dramatic experience fall off. As one moves towards the liberated perspective and leaves the attached perspective behind, any jumps into a very pure version of freedom seem more and more inconsequential. After a certain point, it cannot be perceived as big or dramatic, this is simply the way things are perceived all the time.
Although this kind of experience can be repeated, it is also very common to have just one big experience, and this may commonly be the biggest, most dramatic experience of a meditator's life. On the other hand, it is possible to repeatedly release into a very absolute experience, and some may have more of a predisposition to this kind of thing than others. Psychedelics do help to reach this kind of absolute, but even here some degree of meditative practice makes a big difference.
At any rate, the experience often provides the motivation to get serious about a meditation practice and continue on the path.
