The Śūraṅgama Sūtra, Fascicle Five: The Twenty-five Holy Ones' Perfect Penetration Dharma-gates — Mahāmaudgalyāyana

Original text:大目犍连即从座起。顶礼佛足。而白佛言。我初于路乞食。逢遇优楼频螺。伽耶那提。三迦叶波。宣说如来因缘深义。我顿发心。得大通达。如来惠我袈裟着身。须发自落。心光发宣。如澄浊流。久成清莹。斯为第一。

Explanation: Mahāmaudgalyāyana rose from his seat, bowed at the Buddha's feet, and said to the Buddha: When I first went out begging for food on the road, I met Uruvilvā, Gayā, and Nadī — the three Kāśyapa brothers — who were expounding the profound meaning of the Tathāgata's teaching on dependent origination as they walked. As soon as I heard it, I immediately awakened to the Way and thoroughly understood the dharma of dependent origination. It was the Tathāgata's grace that I attained the fruit of the great arhat of the fourth fruit; instantly the kaṣāya robe draped over my body, my hair and beard fell away by themselves, and the light of great wisdom manifested within my mind — just like washing away a turbid stream, only after long and sustained effort does the muddy water become clear and pure. This is the foremost perfect penetration method I accomplished.

Mahāmaudgalyāyana's self-introduction of his practice method, or one might call it his realization, is the simplest. Why is it so simple? Because he had already cultivated it in previous lives — his manas had already realized it countless times. In this life, at the very moment his new mind consciousness heard the relevant essential teachings, it realized them after but a brief moment of gathering his thoughts, without the trouble of having to train the manas again. His manas was innately resonant with the great arhat of the fourth fruit; his cultivation was extremely high, free of afflictions, with deep and keen wisdom — only the mind consciousness was lacking. When a person of the first fruit returns to the human world, because the manas already realized it in previous lives while the new mind consciousness has not, upon realizing it again, this will be faster than for an ordinary person, but compared with the arhats, it is still quite slow. This is because the manas' wisdom of realizing no-self is still very shallow, the ignorance is still very heavy, and the training and permeation of the mind consciousness is slight, so the mind consciousness's ignorance is heavy. Therefore, upon encountering the Buddha's teachings again, some period of practice is still needed before realizing the fruit once more, though faster than for those who have never realized any fruit. Facts prove that in the process of cultivation and realization, not only is the learning of the mind consciousness important, but the training and permeation of the manas is even more important. In later lives, the manas can permeate and carry along the mind consciousness; thereafter, when the mind consciousness learns new and profound dharmas, it in turn permeates and carries along the manas. The two permeate and carry along each other, and progress on the path of cultivation is then very rapid.