Only by knowing how to apply effort in meditative investigation can results be achieved.

Cultivating meditative concentration ensures that deliberation and contemplative practice (vipaśyanā-caryā) and investigation can proceed; otherwise, the mind becomes scattered after only a brief moment of deliberation. Without meditative concentration, deliberation has no thread to follow, and one's train of thought is not clear either.

The process of applying effort in investigation is extremely complex; the activities of the consciousness of the mind consciousness and the manas are very deep and subtle. If it is not handled well and one does not know how to apply effort, investigation will yield no result. Only when you know how to apply effort and understand the mental activities within can you know how to direct the mind and how to apply effort.

When the mind consciousness and the manas investigate together, the five sense consciousnesses also play a certain role. Otherwise, one would be in the state of the second dhyāna, where the five sense consciousnesses are absent; in that case there would be no deliberation or contemplative practice, and enlightenment would be impossible. The tathāgatagarbha also plays its corresponding role in this process; otherwise, there would be no seven consciousnesses.