An objection runs as follows: if power is an accident and does not persist from an earlier time, on what basis does the deed occur? If earlier power has ceased and later power has not yet appeared, the act seems to occur without power.
The objection assumes that the relevant power must be temporally prior to what it concerns. The answer allows temporal concurrence: the power associated with the action exists at the moment the action occurs.
The argument distinguishes chronological order from explanatory dependence. 'Not existing earlier' does not mean 'not existing at the relevant moment.'