In learning the Dharma, the mind consciousness must investigate together with the manas in meditative concentration.

No matter how much Dharma the mind consciousness knows, if the manas does not know it, one will have doubts, and the mind will not feel steady and grounded. In order to resolve the manas's doubt and prevent the manas from doubting again, one should not let the mind consciousness know alone; the two consciousnesses should investigate together. After personally realizing it, both consciousnesses will know it, and there will be no more doubt. To eradicate doubt and give rise to faith, one must not only eradicate the mind consciousness's doubt, but even more so eradicate the manas's doubt.

Therefore, in studying the Dharma, the mind consciousness should try not to speculate; rather, one should investigate together with the manas within meditative concentration (samādhi). The mind consciousness's doubt is shallow, while the manas's doubt is deep. The deeper the doubt, the greater the relief once it is resolved, the greater the wisdom, and the more the body and mind can be transformed.