Where is the key link in severing the twelve links of dependent origination?

The twelve links of dependent origination span three lifetimes: ignorance (avidyā), volitional formations (saṃskāra), and consciousness (vijñāna) are the antecedent links belonging to past lives; name-and-form (nāma-rūpa), the six sense bases (ṣaḍāyatana), contact (sparśa), feeling (vedanā), craving (tṛṣṇā), and grasping (upādāna) are the links belonging to this life; becoming (bhava), birth (jāti), and aging-and-death (jarā-maraṇa) are the consequent links belonging to future lives. When contemplating this principle, there are two methods: forward and reverse. Contemplating along the twelve links in forward order, one can understand that the bodily, verbal, and mental actions of the six consciousnesses, arising from the manas initiating actions due to ignorance, will lead to the suffering of birth, aging, sickness, and death of the five aggregates in future lives. Contemplating against the twelve links in reverse order has two branches: one branch traces name-and-form back to the karmic actions created by the six consciousnesses in past lives, and then traces further back to the ignorance of the manas; the other branch traces name-and-form back to the source of birth and death, the Ālayavijñāna.

In the first branch of reverse contemplation, tracing backward begins from aging-and-death, proceeding in sequence through birth, becoming, grasping, craving, feeling, contact, the six sense bases, name-and-form, the six consciousnesses, volitional formations, and ignorance. Where lies the key point for ending birth and death in this life? It lies in the four links of grasping, craving, feeling, and contact. Because name-and-form and the six sense bases must be used and cannot be extinguished now—if one tried to extinguish them, one would have to commit suicide, and even death by suicide cannot avoid birth, aging, sickness, and death in future lives. Moreover, the karmic actions of the six consciousnesses are seeds left behind from actions created in past lives; even with repentance, the five aggregates of name-and-form cannot be extinguished. Therefore, to attain liberation from birth and death in future lives, one must focus practice on the four links of contact, feeling, craving, and grasping. The latter three links flow forth from contact; all arise directly or indirectly with contact as their condition. So contact is a crucial link. 

Contact is the contact of the six faculties with the six sense objects, that is, the contact of the inner six entrances with the outer six entrances. Afterwards, the six consciousnesses arise to discern them, then feeling arises, and thus greed and aversion appear; grasping at the states of the six sense objects also follows, and these karmic actions will lead to the suffering of birth, aging, sickness, and death in this and future lives. How can contact with the six sense objects be avoided? One must reduce and eliminate the manas's tendency toward seeking (攀缘). If the manas does not seek after the six sense objects, it will be unwilling to contact them; if there is no contact with the six sense objects, nothing follows afterward, and the mind becomes pure. So the key still lies with the manas. How can the manas be made to stop seeking after the six sense objects? First, cultivate meditative concentration (samādhi); second, understand the principles—contemplate the impermanence and the mark of arising and ceasing (utpāda-nirodha-lakṣaṇa) of the states of the six sense objects. When the manas loses interest in the states of the six sense objects, it will automatically reduce its seeking, and the frequency and duration of contact will decrease; gradually the mind becomes pure. When the mind is pure, there is no feeling; without feeling there is no craving; without craving there is no grasping. 

Since beginningless kalpas, sentient beings' six faculties have been habituated to contacting the six sense objects, and it is very difficult to subdue and remove them all. Sometimes survival necessities force contact, or the contact is passive. Once contact has occurred, one should reduce feeling, or not feel at all. If one achieves a mind without thought at the moment of contact, there will be no feeling; without feeling there is no craving; without craving there is no grasping. To achieve little feeling or no feeling, one must have meditative concentration as well as the wisdom of contemplative practice (vipaśyanā-caryā); only then can the mind be empty, can it be free from marks, can it remain unaffected by states. With a pure mind, one will not grasp at states.

If not being affected by states is rather difficult and cannot be fully achieved, then when experiencing feelings toward states, try not to give rise to greed and aversion. Contemplate the impermanence and falsity of feeling, contemplate the arising-ceasing and impermanence of states, and the mind can be subdued, and greed and aversion can be reduced. Craving is closely connected with feeling; it is very difficult not to give rise to craving while feeling. At this time one must have meditative concentration—the power of concentration must be strong—in order to subdue craving, or even sever it. But severing craving requires meditative concentration at the level of the first dhyāna or above. In the process of cultivating all dharmas, one cannot be apart from meditative concentration. If concentration is shallow, afflictions cannot be subdued, let alone severed, and liberation will be hopeless. 

If one fails at the link of subduing craving, then grasping at what is craved becomes almost inevitable—trying not to grasp is extremely difficult. Grasping is extinguished only when the practice of the third fruit (anāgāmin) is perfected; at the fourth fruit, one no longer grasps. A momentary grasping may be unavoidable, but after that instant it will be severed by wisdom. If such phenomena keep occurring, then one is an arhat whose liberation is not very firm, and before the parinirvāṇa without remainder (Anupadhiśeṣa-nirvāṇa) at the time of death, one must continually engage in preparatory practice in order to attain instantaneous passing into cessation and nirvāṇa. 

To summarize: the four links of contact, feeling, craving, and grasping are all crucial. Only by subduing and severing the preceding link can the following link possibly fail to arise. So the most crucial link for liberation is still contact. In cultivating all dharmas, environment is a very important factor. When the Buddhas and Bodhisattvas cultivated, they were always in quiet and secluded places, undisturbed by people and affairs; there was not so much contact, so their practice progressed quickly and they attained the Way quickly. Therefore, in our cultivation, even when we inevitably have to accord with conditions, we should still create more favorable conditions for quiet practice, minimizing the conditions for contact as much as possible—only then is practice favorable. In bustling places, the Path cannot be accomplished.