Once we have seen our true nature, there is no going back. It is a permanent transformation. It’s like a blind person being given the gift of sight. You’ll never again think of yourself in the old way.
Enlightenment (aka realization) happens suddenly although it may take years of work to be ready for the sudden insight. However it can also happen quickly, if the subject is ready for it. All that it takes is a few minutes is self-inquiry and the willingness to accept the conclusions of your investigation. No special practice or study is required. No particular school of philosophy or religion has any exclusivity to enlightenment. They all talk about it in some fashion of another, although the blade is often dulled by the fact that most of the teachers of the schools (whether they call themselves priest or shaman or philosopher or guru) have not had the direct insight into their own true nature and instead rely on repeating the words of others.
All that is required for enlightenment is the direct realization that you do not exist as an independent being. There are a number of paths we can take to arrive at that realization and none are superior to others. I discuss three of them in “The Three Illusions” but there are others.
When we realize, once and for all, the ultimate statement – “I am That / God / The Universe / All / The One” – then there is nothing else to be done. As the Xin Xin Ming says, “The Great Way is not difficult for those who have no preferences.” All of our problems are predicated on the concept that we are “individual” – separated from the rest of the universe, with our own free will. Once this concept is seen to be false, everything else falls into place. There is nothing to be done and nothing to strive for. If you are already everything (God, The Universe, etc), what is there to do? And who is there to do it? The universe exists and functions according to its nature. You, me, and everyone and every thing *is* the universe. Nothing more and nothing less. The universe is one functioning entity, where nothing can be added and nothing can be removed. In mathematics, we would call is a “set”.
We might think of it as a computer game. Think about a modern console game, like Halo or Call Of Duty. The game contains characters, buildings, inanimate objects, cars, trees, etc. But they are all “the game”. The game is the set of all of those “things”. None of those things is separate from the game. Take away the DVD or console that the game runs on, and you take away the characters and other objects. They are part and parcel of the game.
We, then, are part of the game called “the universe”. It might actually be software running on some form of computer (that’s a theory favoured by at least a small number of theoretical physicsts). The universe might be a lot larger that the console game, but we shouldn’t let its size stop us from realizing that it is still one functioning thing. And we, my friends, are it.