How to Do Well in the Practice of Investigation

When investigating (can-chan), the mind consciousness must thoroughly understand the content to be investigated, give rise to questioning doubt, and condense it into a single point, then hand it over to the manas, so that the manas also gives rise to questioning doubt—thinking about it while walking, sitting, or lying down, from morning till night, refusing to give up until the doubt is resolved.

Why must it be condensed into a single point? Because the manas has no language or words and cannot perform analysis. If the entire meaning is not condensed into a single point, there will be language and words, and the manas will be unable to investigate; only the mind consciousness alone can deliberate and analyze. But when the mind consciousness deliberates and analyzes alone, the depth is relatively shallow and cannot give birth to profound wisdom. In other words, if the manas does not investigate, no wisdom can arise; the wisdom of the mind consciousness alone does not play a decisive role. Only when the manas also has wisdom can it properly grasp the steering wheel of the five aggregates and determine the future destiny of the five aggregates.