@brian64
Someone else shared this recently, it's a popular incorrect translation. (Cut and paste the answer from before)
It was written:
" Jamais on ne fait le mal fi plei nement & fi gayement , que quand on le fait par un faux principe de conf cience . "
Which translates to about:
"Evil is never done fully & gayly only when it is done by a false principle of confidence."

Basically the attributed quote was done with extreme liberties, with minimal regard to the context or proper translation