Arhats and Pratyekabuddhas Both Realize through Direct Perception, Not Inference

The Āgama sūtras describe the pratyekabuddhas' forward contemplation of the twelve links of dependent origination and their reverse contemplation of the twelve links. Although the language describing the pratyekabuddhas' investigation is rather concise and the introduction to their practice is rather simple, the pratyekabuddhas' cultivation was by no means easy; the process in between was winding and arduous. When actually engaging in contemplative practice (vipaśyanā-caryā) and deliberation, they were all in profound meditative concentration (samādhi): the mind consciousness deliberated on one side while the manas deliberated (manasikāra) simultaneously, so of course the results were all realizations. Without meditative concentration, there is only the mind consciousness's deliberation, without the manas's simultaneous deliberation, so realization is impossible—one may arrive at an intellectual understanding, but understanding is of no use.

As for the pratyekabuddhas' concrete practical cultivation process, the Buddha could not disclose it in detail; the purpose was to let later people apply effort themselves and realize it for themselves. Saying too much easily leads people to mere intellectual understanding, and their practice would not be brought to completion, so it could only be stated in that simple way. In those simple deliberations and dialogues, one must never think that the pratyekabuddhas arrived at a result merely through the mind consciousness's reasoning and logical deliberation—to say so would be tantamount to slandering the pratyekabuddhas. The pratyekabuddhas' meditative concentration was extremely profound; the mind consciousness's function absolutely could not occupy the dominant position and could not overwhelm the manas; the manas's investigation and deliberation had to occupy the dominant position. The deeper a person's meditative concentration, the more the manas is employed; conversely, the mind consciousness is used more, relying mainly on the mind consciousness's imagination, reasoning, and speculation, and the manas cannot be put to use.

By the same token, the arhats all had very deep meditative concentration. In observing the five aggregates (pañca-skandha) of the past and the future, they did not use the mind consciousness's reasoning, did not use inference or non-valid cognition, but all observed through direct perception, with the manas participating. Because those material bodies were exactly the same as the current body of the five aggregates, belonging to the same kind, by realizing the current one, they knew the past and the future. For example, suppose there is now a batch of products that need to be inspected; because the products are all identical, by sampling and inspecting just one of them, one knows how all the products are. This of course does not include the case where someone has mixed in other products. On the premise that everything is exactly the same, inspecting one or a few is enough to know the whole. Therefore, the arhats' realizations were all realized through direct perception: what it is, it is; there was no such deliberative mode of imagination, no such deliberative mode of comparison. For a person without meditative concentration, the mind consciousness's deliberative functions of inference and non-valid cognition are unavoidable.