The result of inference cannot be regarded as direct perception (pratyakṣa)

For example, in worldly affairs, when police officers handle a case, they rely on going to the relevant scene to search for evidence of the suspect's crime; they do not handle cases by sitting at a desk analyzing and reasoning with the mind consciousness. Even if the reasoning is correct, it can never be treated as evidence. Although there is reasoning activity in the process of investigation and evidence gathering, the reasoning is for the purpose of finding evidence as quickly as possible; if no evidence is found, such reasoning is discarded and they start over from scratch. Without reliable and accurate evidence, no matter how great the suspicion against a suspect, he cannot be convicted and can only be released without charge. When the court passes judgment on a criminal, it relies entirely on facts and solid evidence; no one has ever convicted a criminal by mere reasoning.

The actual realization of the Buddha-dharma strictly embodies objective laws and is even more rigorous than worldly affairs, admitting not the slightest error. Without conclusive factual basis, the manas cannot realize it—there is simply no way around this.

Suppose A says to the investigators: "Judging by B's daily behavior and his habits, my gold watch must certainly have been stolen by B." The investigators and the court cannot convict B based on A's inference. Even if A's inference is correct, it is not a fact and cannot serve as the basis for conviction. Even if everyone clearly knows that B must be the thief, B still cannot be found guilty.

It is the same with realization in the Buddha-dharma. No matter how powerful one's logical thinking or how correct one's reasoning, it is still not a fact and does not count as realization. In the process of reasoning, one cannot negate oneself so as to eliminate the self-view (ātma-dṛṣṭi), because the manas has not seen the fact and has not been touched in body and mind; therefore it cannot negate the five aggregates (pañcaskandha) as self, and the self-view cannot be eliminated. Without eliminating the self-view, one cannot attain realization. Mere intellectual understanding is permitted, but understanding brings no benefit of merit, cannot attain purity of the Dharma eye, and cannot give birth to the mind of liberation.

For whom does the mind consciousness reason? It reasons for the manas, in order to make the manas understand. For whom does the mind consciousness analyze? It analyzes for the manas, in order to make the manas understand. Because the manas cannot reason or analyze, it often cannot make up its mind when encountering matters. After the mind consciousness has analyzed and reasoned, it will understand certain things and can then make judgments and decisions.