“First, you need to see how your mind attention moves from one thought to another.”
So there are three factors here: 1) YOU (who needs to see) 2) YOUR MIND (attention) and 3) the THOUGHTS that arise one after another. Besides the distinction between brain and mind.
We are all familiar with ‘watching our thoughts’ and so may engage in Anapanasati and Satipatthana. We fail at times and the attention of the mind remains riveted on a particular thought we know we should discard. Then we have failed in only one thing : diverting our attention (because the undesired thoughts are at that time one with the mind, they ARE the mind); so it is the temporarily contaminated mind we are in a struggle with. That simplifies matters somewhat.
Now if it is the gandhabba (where the seat of the mind is) that is involved in doing Anapanasati and Satipatthana, controlling the mind, then the mind must be other than the gandhabba. Or gandhabba and mind will be synonymous,and it will be the gandhabba (the mind) that is trying to control and in time change its own gati. Moreover, on the logical and reasoning plane, the work is done through the medium of the brain, which ‘feeds’ the conclusions to the hadaya vatthu in the gandhabba, where all that is done for better or for worse is registered and which will in time determine one’s destination after death.
And if this were not enough, whoever it is who controls the mind, is, in the final analysis, anatta, a boat to be discarded on reaching the other shore.