Much of the book's greatness stands in Ariosto's ability in handling such a rich and complex material, never losing his balance between comic and tragic moods. Although many episodes have been drawn from a classic source (i.e. Homer's Odissey, just to cite one), Ariosto handles them in a personal style, bestowing on them all the freshness of his Renaissance background.
However, who could ever be so FOOLISH (or ignorant, if you prefere) to say that in Ariosto's "Orlando Furioso" Talkien meets Jonson? Doesn't he know that Ariosto was dead and buried long before Jonson, Swift and Talkien were born???? It were better to say that these genial guys borrowed a little something from Messer Ludovico, weren't it?
:-)