How to Establish Doubt and Inquiry in Chan Meditation

In the practice of mental cultivation, "thought without thought" refers to a state where there are no thoughts on the surface of consciousness, no deliberate contemplation of the Dharma, yet deep within the manas (root consciousness), thoughts still persist. Thoughts linger continuously within the mind; this is investigative contemplation. The practice utilizing the manas is difficult to employ due to insufficient meditative stability. When one truly reaches the stage of applying effort at the level of the manas, even consciousness finds it difficult to observe its workings, for the function of the manas is too subtle and hidden, making it hard to uncover.

In Chan (Zen) investigation, the doubt and questioning should be the closer to the target, the better, and the narrower the scope, the better. This is like searching for a person: setting the search scope nationwide is as good as not setting any scope at all, whereas setting it to a specific region allows one to find the person quickly. The only difference is that the narrower the scope set, the more evidence is required, the more information one must grasp, and the deeper and more refined the wisdom needs to be. The most direct huatou (critical phrase) in Chan is "Who is dragging this corpse?" Attaining realization of the tathagatagarbha (Buddha-nature) within the realm of the formations aggregate (saṃskāra) is the fastest, though the level of attainment may be relatively shallow. Realization attained through the study of consciousness-only (vijñapti-mātra) yields a deeper and more profound level of attainment, while realization attained through understanding the function of the manas is more direct, thorough, and complete.