Yes, what Buddha meant (i believe): In practice one cannot seperate feeling/sensations, perceptions and conscious moments of this or that (vinnana’s).
So, when the awareness of a certain sound arises, this perception of that sound, that is the arising of ear-vinnana’s in the mind. So, the coming and going we notice, is the coming and going of vinnana’s. Vinnana’s, as it were, represent the movement part of the mind. At least, it gives the impression of movement, of coming and going of plans, intentions, thoughts, emotions, sounds, smells etc.
Buddha instructs to see any formations arising in the mind as not me, not mine, not my self and as anicca, dukkha and anatta. If this is realised progressively, mind starts to enter (only by way of speech) into a more and more stable and empty stillness. The mind becomes more and more stable (or tamed ).
The tendency of mind to get lost (grasp at) in her own projections (vinnana’s) weakens.
One can now say, i believe, wisdom of the nature of mind starts to develop. There is a stillness, there is noise. There is the element or aspect of coming and going, an element of movement (vinnana;s arising and ceasing) and there is the aspect of non-movement, of stillness, a space like emptiness an openess, not seen arising and ceasing. Both are aspects of mind, sankhata and asankhata, i believe.
Now knowledge of minds nature becomes more complete because, in general, minds stillness, minds empty and total dispassionate nature, uninclined, that what is never seen coming and going, is often ignored because the obsession with movement (vinnana’s) is so strong.
There is a huge tendency to neglect minds stilled, open and empty nature.
Gradually the knowledge of minds nature evolves while the knowledge of both aspects, sankhata and asankhata, deepens.
There seems to be a taboe to talk about minds stilled, empty and unlimited nature while the sutta’s do speak about it.
I believe the simile of the sea is great to talk about minds nature. A movement part, waves, but also a very deep stilled part, unaffected, unagitated, not influenced by wind.