The Five Aggregates and Six Consciousnesses Are All Tools of the Manas

Question: If all dharmas are realized by the manas, why is it still necessary to give rise to the mind consciousness? 

Answer: The mind consciousness, the five sense consciousnesses, and the five aggregates are all tools that the manas must use. Without these tools, the manas is powerless on its own; it needs the six consciousnesses and the five aggregates to serve it, using the six consciousnesses and five aggregates to greedily pursue all dharmas in the world. Without the six consciousnesses and five aggregates, the manas would be helpless. So although the manas can know many dharmas, it must rely on the mind consciousness to process these dharmas. For example, if ghosts and spirits appear nearby, the manas feels quite frightened, fearing they may threaten it, but it cannot deal with ghosts and spirits itself, nor can it evade them alone. So, while the hairs on its body stand on end, it alerts the mind consciousness to this matter. The mind consciousness then wonders: What exactly is going on? Why do I feel afraid? Why does the surroundings feel eerie, as if something is happening? When the mind consciousness is clever, it thinks it over and comes to know, as much as possible, that there are ghosts and spirits nearby, and then it finds a way to evade them. In this way, the manas achieves its purpose. 

Therefore, although the manas has the capacity of knowing, matters need to be handled by the mind consciousness and the five aggregates. After the manas realizes the dharmas, the pure bodily, verbal, and mental actions need to be carried out by the mind consciousness and the five aggregates; thus the pure bodily, verbal, and mental actions of the six consciousnesses manifest the purity of the manas. However, after cultivating to a considerably high level, when the four dhyānas and eight samādhis have been developed and one possesses immeasurable supernatural powers and powers of the Path, the manas can substitute for the six consciousnesses. At that point, the six consciousnesses need not arise at all; all matters are handled by the manas itself, which is very convenient and effortless. So the function and status of the mind consciousness cannot compare with those of the manas; theirs is forever a master-servant relationship. The master uses the servant to take care of trivial affairs, but when the master's capabilities are great—everything being a modernized program—the servant is no longer needed, and the master can handle everything well and handle it splendidly.