...stream entrant (sotapanna). The Buddha's senior disciple Sariputta explains that the "stream" is a metaphor for the eightfold path and that a person who has entered the stream is one who has made that path his or her own. It is difficult to find an English equivalent for this evocative and core idea. As a metaphor "to enter a stream"; implies that one is no longer trapped in cycles of habitual behaviour that lead nowhere but has been released from the grip of those habits to flow freely without impediment. This free flow is experienced as a way of being alive that affirms one's autonomy and integrity...A free-flowing life is contextualized within a framework of commitments and values. Just as a stream is guided along its course to the ocean by the banks between which it flows, so the eightfold path is sustained and directed by...the dharma...This way of life is autonomous in the sense of its no longer being determined by instinctive reactivity-in particular, the impulses of greed, hatred and confusion. Indeed, the path itself has its source in a person's direct experience of the suspension or absence of these impulses, which is the definition of nirvana. This does not mean, however, that having once glimpsed nirvana, innate reactivity will never recur. Gotama was not psychologically naive. The experience of nirvana marks a turning point in an individual's life, not a final and immutable goal. After the experience one knows that one is free not to act on the impulses that naturally arise in reaction to a given situation. Whether one chooses to act on impulses is another matter. Yet it is precisely this freedom that serves as the wellspring from which the stream of the path begins to flow.
Stephen Batchelor, After Buddhism: Rethinking the Dharma for a Secular Age