To do penance is to bewail the evil we have done, and to do no evil to bewail.
I can hardly believe that I even know this, but I am aware that Noah Webster's original dictionary, apart from being the first truly American lexicography, was a kind of line in the sand. It claimed a very discrete, American form of the English language, explicitly to compare it to the English of our erstwhile colonial masters who had been operating under Dr. Johnson's dictionary rules for well over a century.