Facing the entrance to the centre or extreme eastern chapel, that of San Ildefonzo, the back of the high altar, or, as it is vulgarly called, the Trascoro, is--not adorned, would it were possible not to say disfigured, by an immense mass of sculpture called the Transparente. It is not easy to imagine the reason of this altar-piece having received its name, for it is not more transparent than any other mountain--never was witnessed so lamentable a mis-application of riches and labour! Some of the marble was brought from Carrara; the rest is not of a very good white, and being thus exposed to an unfavourable contrast, adds to the displeasing effect of the unwieldy forms which enter into the composition of this huge blunder of art--this pile of masses on masses of ugliness. At the sight of a large spherical form rising abruptly from the surface of some shaft of a pillar, you step back, and discover that it forms part of the posteriors of a corpulent cherub, as large as the column itself, which he has thus unmercifully annihilated, in order to save himself the trouble of passing a few inches to the left or right. But it is needless to notice the details of this piece of sculpture, which being the largest, and occupying the most conspicuous position in the whole church, forcibly attracts the attention which, but for that circumstance, one would rather bestow in another direction. It is a relief to take one's station on the shining mahogany benches adjoining the wall of the opposite chapel of San Ildefonzo; and to contemplate its chaste style and graceful proportions, and the handsome tombs which occupy its octagonally divided walls. The piece of sculpture in marble, placed over the principal altar, is undeserving of its conspicuous situation. It represents the Vision of San Ildefonzo, to which we shall shortly have occasion to direct our attention.