Imagination and conjecture are utterly unreliable methods of practice

Because sentient beings have limited wisdom and insufficient meditative concentration (samādhi), they are unable to contemplate deeply, and the deliberation (manana) of the manas cannot operate either. For some of the deeper dharmas, they habitually resort to imagination and speculation—and imagination and speculation are functions of the mind consciousness, containing not the slightest wisdom of the manas. The most serious form of imagination and speculation is to talk carelessly, saying: after enlightenment, one can observe how the eighth consciousness gives rise to the sense faculties and the material world. The faculties here refer to the physical faculties, the body. As for how the eighth consciousness uses seeds to give rise to the physical faculties bit by bit, how it gives rise to the eye faculty, ear faculty, nose faculty, and tongue faculty—after enlightenment, with another incalculable eon of cultivation, one might perhaps observe a little; with two incalculable eons, one could roughly observe a great deal. The material world refers to the universe, the vessel-world, the spatial environment in which sentient beings live. As for how the eighth consciousness uses seeds to give rise to the universe and the vessel-world, even after enlightenment and another incalculable eon of cultivation, one might perhaps still not be able to observe it; with two incalculable eons, one could roughly observe some of it.

The elements (dhātu) refer to the eighteen elements: the six faculties, six sense-objects, and six consciousnesses. As for how the eighth consciousness uses seeds to give rise to the six faculties and six sense-objects, even after enlightenment and another incalculable eon of cultivation, it would still be very difficult to observe; with two incalculable eons, one could roughly observe some of it. As for how the eighth consciousness uses seeds of consciousness to give rise to the six consciousnesses, after enlightenment and another incalculable eon of cultivation, one could observe some of it, but not observe it completely and fully. Yet no matter what one can observe, if one's own mind is not thereby changed, and one's bodily, verbal, and mental actions do not change as a result of that observation, then the so-called observation is not observation at all, but imagination and conjecture. Imagination and conjecture are the modes and methods of the mind consciousness's thinking, and do not involve the deliberation of the manas, the sovereign consciousness. What is imagined and conjectured therefore has no force of effect: it cannot transform one's bodily, verbal, and mental actions, cannot eliminate the seeds of afflictions and unwholesome karma, and carries no pure merit and benefit.