Only with Complete Meditative Concentration Is Enlightenment Possible.

The so-called contemplative practice (vipaśyanā-caryā), before realization, is called deliberation and investigation (manasikāra)—deep and subtle deliberation, exploration, probing, searching, and sustained examination (vicāra); it is not shallow mental activity, and it must land in the manas. After realization, it is called observation—observing directly, in the present, the various operations of the tathāgatagarbha within the body of the five aggregates (pañca-skandha), observing the mysteries of all dharmas; even then, there must still be deeper and subtler deliberation and investigation, all of which must land in the manas. Contemplative practice before realization and after realization must both take place in preparatory concentration (anāgamya-samādhi) or in the concentration of the first dhyāna; without meditative concentration, it is purely the learning, understanding, and reasoning activity of the consciousness, and the deliberation is very shallow. Even with meditative concentration, if the concentration is relatively shallow, the power of deliberation is also insufficient, remaining only in the mind consciousness, and one cannot attain enlightenment and realization. The contemplative practice of the Four Noble Truths, the contemplative practice of realizing the tathāgatagarbha, the contemplative practice of the contemplation of illusoriness, the contemplative practice of the contemplation of mirage-like appearances, the contemplative practice of the contemplation of dream-likeness, the contemplative practice of the contemplation of mirror images—these contemplative wisdoms progress layer by layer, with the wisdom of contemplative practice becoming ever deeper and subtler.

The so-called enlightenment must be the personal realization of the tathāgatagarbha by the mind consciousness and the manas; it is not that understanding the principle of the tathāgatagarbha counts as enlightenment. Those principles can be known through various channels, but realizing the tathāgatagarbha must be done through investigating Chan and personally realizing it. Enlightenment is not knowledge and principles learned from others, but what the manas personally realizes through effective investigation.