Yah, yah. That's where I found it, too, but there seems to be (a) no way to contact the Portia people to ask them from whence they got it nor (b) any other citation to it on the web -- at least not according to Google. Our ranks are so filled with erudite people that I thought/hoped that someone would pull a dusty volume of "The Truly Obscure Works of Martin Luther" off their home shelf and find the pencil-marked passage from whence this comes.