Metastasio was fettered by a double set of rules; for he was compelled to attend at once to the dramatic unities of Aristotle, and the musical restraints of the opera. It was no common genius which, amidst such difficulties, could produce a series of dramas which should not merely charm the world, when arrayed in the enchanted garb of the opera, with all the attractions of music and scenery, but form a perpetual subject of pleasing study to the recluse, far from the pomp and magnificence of theatric representation. It is impossible to imagine any thing more attractive than his dramas, considered as visionary pieces. Formed on the events of the ancient world, he depicts, under the name of Alexander, Titus, Dido, Regulus, Caesar, and Cleopatra, ideal beings having about as much resemblance to real mortals as the nymphs of the ballet have to ordinary women, or the recitative of Mozart to the natural human voice. But still they are very charming. If they are not a feature of this world, they are a vision of something above it; of a scene in which the littlenesses and selfishness of mortality are forgotten; in which virtue is generally in the end triumphant; in which honour in women proves victorious over love, and fortitude in men obtains the mastery of fortune. Generosity and magnanimity beyond what could have been even conceived, often furnishes the _denouement_ of the piece, and extricates the characters from apparently insurmountable difficulties. There can be no doubt this is not human life: Alexander the Great, Dido, Regulus, are not of every day's occurrence. But the total departure of such representations from the standard of reality, appears less reprehensible in the opera than the ordinary theatre, because the singing and recitative at any rate remove it from off the pale of mortality. We take up one of his dramas as we go to the opera, not to see any picture of actual existence, or any thing which shall recall the experienced feelings of the human heart, but to be charmed by a fairy tale, which, if it does not paint the stern realities of life, at least charms by its imagination.