  In a recent paper [ J. Stat. Mech. P07006 (2004)], E.G.D. Cohen and David
Mauzerall (CM) have argued that the derivation of the nonequilibrium work
relation given in [C. Jarzynski, Phys. Rev. Lett. 78, 2690 (1997)] is flawed.
Here I attempt to answer their criticisms, both by presenting a detailed
version of that derivation and by addressing specific objections raised by CM.
The derivation presented here is in fact somewhat stronger than the one I gave
in 1997, as it does not rely on the assumption of a weak coupling term between
the system of interest and its thermal environment.
