何用疏親 What is the use of not-self and self?
欲取一乘 If you want to follow the One Way
勿惡六塵 Have no aversion to the six sense-objects
六塵不惡 Having no aversion to the six sense-objects
還同正覺 Is equal to true awakening
David J. Kalupahana (1975) explains why many Buddhists believed that meditation consisted in shutting down sense-perception and thoughts—-a practice that Zen masters uniformly opposed:
The process of perception [of the world], which the Upanishadic thinkers also explained on the basis of a metaphysical self (atman), received a causal explanation in the hands of the Buddha. For him, this was a problem of prime importance because he realized that all the misery and unhappiness in the world were due to the evils associated with sense perception. The Buddha thus found it necessary to explain clearly how sense perception takes place. He realized that a proper understanding of the sensory process would give insight into the origin of suffering as well as into the way one can attain freedom from suffering. Hence, in the Sarrzyutta Nikaya, the higher life (brahmacariya) lived under the Buddha is said to be aimed at understanding the sense organ, the sense object, and sense contact, i.e., sense perception, because it is sense perception that leads to suffering. (p. 121)
If you have awakened to the prajna samadhi, you have no-thought. What is no-thought? The doctrine of no-thought means the following: even though you see all things, you do not become attached to them, but, always keeping your own nature pure, you cause the six thieves (sense-objects) to exit through the six gates (sense-organs). Even though you are in the midst of the six contaminations, you do not stand apart from them, yet are not sullied by them, and are free to come and go. This is the prajna samadhi, and freedom and liberation are attained through the practice of no-thought. If you do not think of the myriad things but always cut off your thoughts, you will be Dharma-bound: this is an erroneous view. One who grasps the Sudden-School doctrine of no-thought penetrates into all things thoroughly and sees the realm of the Buddha. One who grasps the Sudden-School doctrine of no-thought reaches the stage of Buddha. (Hui-neng: Mahaprajnaparamita)
The Third Patriarch has said: “If one wishes to gain true intimacy with enlightenment, one must not shun the objects of the senses.” He does not mean here that one is to delight in the objects of the senses but, just as the wings of a waterfowl do not get wet even when it enters the water, one must establish a mind that will continue a true koan meditation without interruption, neither clinging to nor rejecting the objects of the senses. A person who fanatically avoids the objects of the senses and dreads the eight winds that stimulate the passions,unconsciously falls into the pit of the Hinayana and never will be able to achieve the Buddha Way.
Yung-chia has said: “The power of the wisdom attained by practicing meditation in the world of desire is like the lotus that rises from fire; it can never be destroyed.” Here again, Yung-chia does not mean that one should sink into the world of the five desires. What he is saying is that even though one is in the midst of the five desires and the objects of the senses, one must be possessed of a mind receptive to purity, as the lotus is unstained by the mud from which it grows.
Moreover, even should you live in the forests or the wilderness, eat one meal a day, and practice the Way both day and night, it is still difficult to devote yourself to purity in your works. How much harder must it be then for one who lives with his wife and relatives amid the dusts (that perceived by the six senses) and turmoils of this busy life. But if you do not have the eye to see into your own nature, you will not have the slightest chance of being responsive to the teaching. Therefore Bodhidharma has said: “If you wish to attain the Buddha Way, you must first see into your own nature.”
If you suddenly awaken to the wisdom of the true reality of all things of the One Vehicle alone, the very objects of the senses will be Zen meditation and the five desires themselves will be the One Vehicle.* Thus words and silence, motion and tranquility are all present in the midst of Zen meditation. When this state is reached, it will be as different from that of a person who quietly practices in forests or mountains, and the state to which he attains, as Heaven is from Earth. When Yung-chia speaks of the lotus facing the flames, he is not here praising the rare man of the world who is practicing Buddhism. Yung-chia penetrated to the hidden meaning of the Tendai teaching that “the truths themselves are one.” He polished the practice of shikan in infinite detail, and in his biography the four dignities (sitting, standing, moving, lying down) are praised as always containing within them the dhyana contemplation. His comment is very brief, but it is by no means to be taken lightly. When he says that dhyana contemplation is always contained within the four dignities, he is speaking of the state of understanding in which the two are merged. The four dignities are none other than dhyana contemplation and dhyana contemplation is none other than the four dignities. When Vimalakirti says that the bodhisattva without establishing a place for meditation, practices amidst the activities of daily life, he is speaking about the same thing. (Orategama)
*One Vehicle: Attaining enlightenment on your own, without the help of a master
Kalupahana, David J. Causality: The Central Philosophy of Buddhism. Honolulu: The University Press of Hawaii. 1975.
Yampolsky, P. B. The Zen Master Hakuin: Selected Writings (Translated by Philip B. Yampolsky). Columbia University Press: New York, 1971. https://terebess.hu/zen/Orategama.pdf