Thank you vilas,
“…able to catch before it happens”
To ‘catch’, yes, but that is only phase one. It does not mean that it is always succeeded by phase 2, the abandoning, what you term as ‘the reversing’- not at once, anyway.
Sometimes the sense input or the mental input ( I mean two different things here) may be too enticing to dispel at once, although the awareness of the need to do so is there. When this happens, I may dwell there for a while, or sometimes a while longer, but I am fairly satisfied that even if I allow that, i.e. if I am unable to repel them on their arising, I feel I am making progress.
The contemplation of asubha I have found to be fundamental here, as it leads to seeing further into the anicca nature, or other aspects of the anicca nature, or these may well be the same aspects viewed as arising from different causes.
Thank you for the encouragement, vilas
Much Metta