Maitreya: World-honored One, how does this cultivation [of meditation] produce the great insight? 

Buddha: Good son, when they [aspirants] become aware of the six supports, they attain insight into the nature of thought. 

The first is that they know well the arising of thought. 
The second is that they know well the abiding of thought. 
The third is that they know well the departure of thought. 
The fourth is that they know well the increasing of thought. 
The fifth is that they know well the diminution of thought. 
The sixth is that they know well the methods. 

They know well the arising of thought, for they truly know the differences that engender thought in its sixteen activities, and this is what is meant by knowing well the arising of thought