Fielding digression in TOM JONES - the marvellous [sic]

"The same thing which is impossible may yet be probable, . . ."

http://books.google.com/books?id=Bdy0LmSivFcC&pg=PA272&lpg=PA272&dq=Fielding+possible+probable+Tom+Jones&source=bl&ots=5gbn4aQVeK&sig=y8q09fxogvK_NY0gXMM_PMae838&hl=en&sa=X&ei=c2tRT9O2Muyx0QGO4pG9DQ&ved=0CCAQ6AEwAA#v=onepage&q&f=false