I agree with heisenberg's choice. There are only two possible authors of the two works represented by the two grids (and the title words). Percy Bysshe Shelley is one, but there is no doubt about his authorship. Therefore the intended one must be the classical author, where there is some divergence of opinion on the matter, particularly with regard to the second work. This seems to be implied in the preamble phrase "traditionally ascribed to."