Sundarananda's Dharma Gate of Perfect Penetration through the Nose Consciousness in the Śūraṅgama Sūtra

Original text:孙陀罗难陀。即从座起。顶礼佛足。而白佛言。我初出家。从佛入道。虽具戒律。于三摩提。心常散动。未获无漏。世尊教我。及俱絺罗。观鼻端白。我初谛观。经三七日。见鼻中气出入如烟。身心内明。圆洞世界。遍成虚净。犹如琉璃。烟相渐销。鼻息成白。心开漏尽。诸出入息化为光明。照十方界。得阿罗汉。世尊记我。当得菩提。佛问圆通。我以销息。息久发明。明圆灭漏。斯为第一。

Explanation: Sundarananda rose from his seat, bowed at the Buddha's feet, and replied to the Buddha: When I first left home, I entered the Path by following the Buddha. Although I observed the precepts well, my meditative concentration (samādhi) was not sufficient; my mind often had scattered and restless phenomena, so I had not eradicated afflictions and had not attained the untainted (anāsrava). The World-Honored One taught me and Mahākauṣṭhila to contemplate the white vapor emitted from the breath going in and out at the tip of the nose. At first I contemplated carefully within meditative concentration, and after twenty-one days, I saw the breath drawn in and out through the nose like smoke. My body and mind were inwardly luminous and clearly aware, and I could perfectly perceive that the great thousand worlds everywhere were empty and pure, as clear and transparent as crystal. At that time the breath between the nostrils turned white, my mind opened, wisdom surged forth, and afflictions were exhausted. All the outgoing and incoming breaths transformed into light, illuminating the worlds of the ten directions. In this way I attained the fruit of an arhat, and the World-Honored One prophesied that I would in the future accomplish the Buddha Way. The Buddha asked me about the dharma gate of perfect penetration: I contemplated the breath, and when the observation became deep and subtle, I extinguished the breath. After the breath had ceased for a long time, the inner wisdom was born; I clearly recognized that the breath at the tip of the nose, as well as the five aggregates and eighteen realms, are all empty and illusory. When wisdom was complete, afflictions were exhausted. I take this method as the foremost dharma gate of perfect penetration.

When Sundarananda first contemplated the breath, he had already attained the fruit of a srotāpanna or a sakṛdāgāmin, but his meditative concentration was not very good; his mind had scatteredness and he did not have the concentration of the first dhyāna, so he was not yet an anāgāmin. After contemplating the breath at the tip of the nose, his meditative concentration grew better and better, the power of concentration emerged, and his observation became deep, subtle, and minute; he then observed that the breath at the tip of the nose was like smoke. Without sufficient power of concentration, one cannot discover this phenomenon. The air and breath that are normally invisible became visible at this time, extremely subtle like smoke. This shows that the breath is also material form (rūpa), composed of various particles of the four great elements; it is only too subtle, and those without profound meditative concentration, whose minds are coarse, cannot see it. Being able to see subtle dharmas is great wisdom. Because he opened great wisdom, he inwardly saw through body and mind, and outwardly clearly perceived the world, knowing that the world, body, and mind are illusory and unreal. Supernatural powers appeared, afflictions were exhausted, and he became a great arhat of the fourth fruit.