There exists no such picture of a sacrifice by Titian, and what Keats was thinking of, I feel sure, was the noble 'Sacrifice to Apollo' by Claude from the Leigh Court collection, which he had seen at the British Institution in 1816 (hung, as it happened, next to Titian's Europa from Cobham Hall), and which evidently worked deeply on his mind. To memory of it is probably due that magic vision of a little town emptied of its folk on a morning of sacrifice, which he evoked a year later in the ode on a Grecian Urn. It shows to the right an altar in front of a temple of Apollo, and about the altar a group including king and priest and a young man holding down a victim ox by the horns; people with baskets and offerings coming up from behind the temple; and to the left tall trees with a priest leading in another victim by the horns, and a woman with a jar bringing in libation; a little back, two herdsmen with their goats; a river spanned by a bridge and winding towards a sea-bay partly encircled by mountains which close the view, and on the edge of the bay the tower and roofs of a little town indistinctly seen. Recollection of this Claude leads Keats on quickly to that of another, the famous 'Enchanted Castle,' which he partly mixes up with it, and partly transforms by fantasy into something quite different from what it really is. He forgets the one human figure in the foreground, describes figures and features of the landscape which are not there, and remembering that the architecture combines ancient Roman with mediæval castellated and later Palladian elements, invents for it far-fetched origins and associations which in a more careless fashion almost remind one of those invented by Pope for his Temple of Fame. (A year later, all this effervescence of the imagination about the picture had subsided, and the distilled and concentrated essence of its romance was expressed--so at least I conceive--in the famous 'magic casement' phrase at the end of the Nightingale ode).[7]
FROM AN ENGRAVING BY VIVARES AND WOOLLETT AFTER CLAUDE]
From this play of fancy about two half-remembered pictures Keats turns suddenly to reflections, which he would like to banish but cannot, on the 'eternal fierce destruction' which is part of nature's law:--