If it's any encouragement, I managed to work out what was going on and complete the grid without knowing the quotation and its originator.
Finding both of these, for me, was harder than filling the grid. I also found it a little odd that there was no requirement to "show your workings" by entering the originator's name under the grid as is so often the case.
So in theory this puzzle could have been won (had there been a prize) by a submitter who hadn't fully cracked it. But a wonderful puzzle all the same.