One of the most striking features of the Aunupada Sutta is how deliberately it dismantles the romantic idea of awakening as a single, dramatic breakthrough. Instead, the Buddha presents Sariputta’s realization as a sequence of careful experiments. Each attempt isolates a different domain of experience, examines it with precision, and then—crucially—lets it go when its limitations become clear.
By the fifth attempt, Sariputta has already investigated obstacles, mind, body, and feeling. What remains is subtler and more elusive: perception itself. This is not accidental. Perception is the quiet architect of our lived world. It divides experience into objects, assigns boundaries, and gives rise to the sense that there is a perceiver here and a perceived world over there. If that structure remains unquestioned, awakening remains theoretical.
In this stage, as described in the Aunupadasutta, Sariputta inclines the mind toward the perception of infinite space. This is often misunderstood as a metaphysical claim or a mystical vision of the cosmos. In fact, it is far more practical. Sariputta is not trying to believe in infinity; he is training the mind to resist its habitual urge to differentiate.
Ordinarily, perception is busy carving reality into parts. This object, not that one. Inside, outside. Subject, object. The perception of infinite space works in the opposite direction. It softens edges. It loosens boundaries. Experience appears as a continuous field rather than a collection of things. In this way, Sariputta temporarily suspends the mind’s default organizing principle and observes what remains.
What remains is revealing. The usual sense of separation weakens. The compulsion to locate oneself at the center of experience loses some of its force. And yet—this is the critical insight—Sariputta does not stop there. He does not declare victory. He does not confuse expansiveness with liberation.
Instead, he does what he has done in every previous attempt: he investigates. He observes the arising of this perception of infinite space. He notes its subtle pleasure, its tranquility, its refinement. And he watches it pass away. From this, a decisive conclusion emerges. Even this vast, seemingly boundless perception is conditioned. It depends on causes. It arises due to intentional mental activity. And because it arises, it must cease.
This recognition marks the maturity of Sariputta’s inquiry. Spaciousness, no matter how compelling, is still a perception. And perception—by definition—is part of the machinery that constructs experience. If awakening is unconditioned freedom, then no conditioned perception, however sublime, can be the final answer.
Sariputta’s fifth attempt is therefore not a failure but a refinement of understanding. He has learned that dissolving boundaries is not the same as ending construction altogether. The mind may stop dividing the world into objects, but it is still actively shaping experience. Seeing this clearly, Sariputta knows there is still work to be done.
For modern readers and practitioners, this moment carries a quiet warning. Expansive states can be persuasive. They can feel final. Sariputta shows us another way: appreciate their value, learn from them deeply, and then move on without clinging. Awakening, he demonstrates, does not lie in any particular perception—not even one as vast as infinite space—but in understanding perception itself.
