Yogācārabhūmi Śāstra, Volume Thirty-Four (Forty)

Original text:由如是等。比度增上作意力故。于有他世诸行生起。获得决定。如是略由三种增上作意力故。寻思观察。内外诸行是无常性。谓净信增上作意力故。现见增上作意力故。比度增上作意力故。于前所举。能随顺修无常五行已。辩变异灭坏二行。

Explanation: Because of the above power of intensified attention (adhimātra-manaskāra-bala) based on inference, one gains certainty regarding the arising of the volitional formations of past and future lives. Broadly speaking, through three kinds of power of intensified attention, one can investigate and observe that the internal and external volitional formations are impermanent in nature. The three kinds of power of intensified attention are: the power of intensified attention of pure faith, the power of intensified attention of direct perception, and the power of intensified attention of inference. Regarding the internal and external volitional formations listed earlier, one can accordingly cultivate the five contemplations of impermanence, and then discern the two contemplations of mutation and destruction.

When it is necessary to contemplate the impermanence of the five aggregates (pañca-skandha) of past and future lives, one must, on the basis of directly perceiving the five aggregates of this life as they truly are through contemplative practice (vipaśyanā-caryā), correctly infer and contemplate the five aggregates of past and future lives in order to attain realization and knowledge. The two dharmas being compared through inference must be of the same kind; dharmas that are not of the same kind cannot be compared by inference. On the basis of directly perceiving the present five aggregates as they truly are through contemplative practice, one can correctly infer and contemplate the five aggregates that have already passed, as well as the five aggregates that will arise in the future. In this way one can attain realization and knowledge, and the mind can gain certainty and confirmation regarding the impermanence of all volitional formations.