Yogācārabhūmi Śāstra, Fascicle 34 (36)

Original text: 故依现见增上作意。应正比度。云何比度。谓彼诸行。要有刹那生灭。灭坏方可得有前后变异。非如是住得有变异。是故诸行。必定应有刹那生灭。彼彼众缘和合有故。如是如是诸行得生。生已不待灭坏。因缘自然灭坏。如是所有变异因缘。能令诸行转变生起。

Explanation: Therefore, relying on the power of intensified attention (adhimātra-manaskāra-bala) of what is directly seen, one should correctly infer, and thereby know the momentary arising, ceasing, and transformation of the volitional formations of form. How does one infer? One should cognize it thus: the volitional formations must have momentary arising and ceasing; only when the formations of form have ceased and decayed can the variations before and after be observed. It is not that they can be known to vary while abiding unchanged in that way. Therefore, it is said that the volitional formations must necessarily have momentary arising and ceasing. Because they arise from the combination of various conditions, these volitional formations come into being in such and such a way. After they arise, without waiting for the formations themselves to decay, when their combining conditions perish, the volitional formations naturally decay and perish. Therefore, it is said that all the conditions that cause variation in the volitional formations can bring about their transformation and arising.

Inference is also called anumāna (inference); only correct inference based on what is directly perceived can yield a true result. That is, the basis of inference is direct perception—facts—so that the result of the inference may possibly be factual. Otherwise, it is incorrect inference, and the result of the inference will not be true and cannot be relied upon.

The volitional formations of form are the operation of material form and the aggregate of form. Although the volitional formations of form are directly present and visible through direct perception, the moment-by-moment arising, ceasing, and transformation of material form cannot be directly seen due to insufficient power of meditative concentration and insufficient power of wisdom (prajñā-bala); therefore, one must perform correct inference based on the volitional formations of form that are directly and truthfully seen. Material form must constantly arise, cease, and decay in order to exist and manifest—only then are there volitional formations of form; only with variation before and after are there volitional formations of form. If material form did not vary, there would be no formations, and the dharma would not exist. Therefore, the momentary arising, ceasing, and transformation of the volitional formations of form must be correctly inferred on the basis of the direct perception of form, in order to be realized and truly known.