In the practice of Vipassana we try to stay in “the present moment.” Everyone knows what the “present” means: Now. But what, precisely, is a “moment”? How long does it last? And when does the present moment become the past?

In Vipassana the word “moment” has two definitions. The first could be called the “practice-moment.” (“Practice” refers, of course, to meditation practice.) The second is the moment of consciousness itself.

The length of the practice-moment is determined by the object. For instance, when you touch the toe to the floor in the walking exercise, that is one practice-moment; but it’s shorter than the act of moving the foot forward. As soon as you complete a step, that moment is over. If you continue thinking about it, you’ve strayed away from the present. What is the present? Only the object that’s arising right now. We could say that the practice-moment is the length of time you focus on an object before letting it go and moving on to the next one. A single practice-moment is about one to three seconds long. It varies depending on the form you’re observing.

The moment of consciousness, the second definition, refers to one mind-moment (cittakkhana) arising and disappearing. The rate of this moment is incredibly fast and doesn’t vary. A moment of consciousness is the smallest unit by which we can “measure” ultimate reality. A single one of these blips is millions of times shorter than a two-second practice moment. These mind-moments are appearing and vanishing one by one all the time, whether or not we recognize them.

It is possible for the meditator to progress from observing the first kind of moment to seeing the second. As mindfulness gets sharper and faster, the student begins to bridge the gap between the practice-moment and the moment of consciousness. When that happens, the meditator might focus on one walking step, for example, and perceive several moments arising and passing away before the movement of the foot is finished. Like a meteor zipping across the sky, there might be a sense of great speed as mindfulness sees something in a split second. The meditator may find that, as soon as he focuses on anything, it bursts and dissolves immediately. The moments become shorter as mindfulness is able to “cut” things faster.

When mindfulness is quick enough, the student will experience the moment of consciousness itself. He will see one mind-moment arising and vanishing in clear detail. This is to witness the truth of experience, undistorted by delusion. It is a glimpse of ultimate reality. He then understands one of the three characteristics: impermanence, unsatisfactoriness, or impersonality. This understanding is an immediate vision, not a thought.

The aim of Vipassana practice is to make one mindful enough to perceive a single moment of consciousness arising and disappearing. One need only experience three or four such moments in a row in order to reach enlightenment. Indeed, even perceiving one moment of ultimate reality is a great boon for the meditator. It’s said that such an experience, by which meditator attains the level called “lesser streamwinner” (culla-sotapanna), will continue to give benefit for three successive lifetimes.