i think he means the "m" is generated after the collision, or something like that
if you worry about before and after the collision, look at the formula: time is a factor on both sides of the equation, so it cancels itself out, or something.....
would you believe that "imagination" is the "real" cause ?
we think and are taught that there is coherence between everything: as above, so below, as in nature, so in our minds
in reality, the universe and cosmic laws are just a reflection of a higher reality, and there is no coherence between shadows, or something like that