Where is the key link for bringing an end to the twelve links of dependent origination?

The twelve links of dependent origination span three lifetimes: ignorance, volitional formations, and consciousness are the antecedent links (pūrvāṅga) of the previous life; name-and-form, the six sense bases, contact, feeling, craving, and grasping are the links of the present life; and existence, birth, and aging-and-death are the consequent links (paścādṅga) of future lives. When contemplating this principle, there are two methods: following the sequence and reversing the sequence. Contemplating in the forward order of the twelve links, one can understand how the manas, due to ignorance, gives rise to volitional formations, which produce the bodily, verbal, and mental actions of the six consciousnesses, leading to the suffering of birth, aging, sickness, and death of the five aggregates in future lives. Contemplating in the reverse order of the twelve links has two branches: one branch traces name-and-form back to the karmic actions created by the six consciousnesses in the previous life, and then traces further back to the ignorance of the manas; the other branch traces name-and-form back to the ālayavijñāna, the source of birth and death.

In the first branch of reverse contemplation, one traces backward starting from aging-and-death, successively tracing back to birth, existence, grasping, craving, feeling, contact, the six sense bases, name-and-form, the six consciousnesses, volitional formations, and ignorance. Where is 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 the birth, aging, sickness, and death of future lives. Moreover, the karmic formations of the six consciousnesses are seeds left over from actions created in previous 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 cultivation 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. Thus contact is a crucial link. 

Contact is the contact of the six sense faculties with the six sense objects—that is, the contact of the inner six sense bases with the outer six sense bases. Afterwards, the six consciousnesses arise to discern, and then feeling arises; thus greed and aversion appear, and grasping at the objects of the six sense objects also follows, and these karmic formations 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 grasping. If the manas does not grasp at the six sense objects, it will be unwilling to contact them; if there is no contact with the six sense objects, nothing follows, and the mind becomes pure. So the key still lies with the manas. How can the manas be made to stop grasping at the six sense objects? First, cultivate meditative concentration (samādhi); second, understand the principles—contemplate the impermanence and arising-and-ceasing nature of the objects of the six sense objects. When the manas loses interest in the objects of the six sense objects, it will automatically reduce its grasping, 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 contact is necessary for survival, or is passive. Once contact has occurred, one should reduce feeling, or not feel at all. If one can be without mind at the moment of contact, there is 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 contemplative wisdom (vipaśyanā-caryā); only then can the mind be empty, be detached from signs, and remain unaffected by objects. With a pure mind, one will not grasp at objects.

If not being affected by objects is difficult and cannot be fully achieved, then when experiencing objects, one should try not to give rise to greed and aversion, and should contemplate the impermanence and falsity of feeling, and contemplate the arising-ceasing and impermanence of objects; then the mind can be subdued and greed and aversion reduced. Craving is closely connected with feeling; it is difficult not to give rise to greedy craving while feeling. At this point, meditative concentration is essential—the power of concentration must be strong in order to subdue craving, and even to eliminate it. But eliminating 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 eliminated, and liberation will be hopeless. 

If one fails at the stage of subduing craving, then grasping at what is craved becomes almost inevitable—it is extremely difficult not to grasp. Grasping is extinguished only when the cultivation of the third fruit (Anāgāmin) is brought to completion; at the fourth fruit, there is no more grasping. A momentary grasping may be unavoidable, but after the instant it will be severed by wisdom. If such phenomena keep occurring, this is an arhat whose liberation is not yet firm; before the nirvāṇa without remainder (anupadhiśeṣa-nirvāṇa) at death, one must continually make intensified effort (adhimātramanaskārabala) in order to attain instantaneous passing and nirvāṇa. 

To summarize: the four links of contact, feeling, craving, and grasping are all crucial. Only when the preceding link has been subdued and severed 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 always did so in quiet and secluded places, undisturbed by people and affairs; with so little contact, their practice advanced rapidly and they attained the Way quickly. Therefore, in our cultivation, even when we inevitably have to accord with conditions, we should still create more conditions and opportunities for quiet practice, minimizing the conditions for contact as much as possible—only then is cultivation feasible. In bustling, noisy places, the work of the Path cannot be accomplished.