The reader, who has followed us through this review of “Don Giovanni,” clinging always to the musical thread of interpretation, will find himself as little able as ourselves to sympathize with the regret, so frequently expressed, that Mozart should have prostituted his genius in this composition, by the false marriage of so much divine music with an unworthy subject. We believe the marriage was a true one. He did not merely cater to a low, licentious taste, in the selection of this story. Never was a choice made more heartily. Or, if he did not himself _choose_ the plot, yet he _fell in_ most heartily, and as it were, by a providential correspondence with the invention of Da Ponte—as heartily as he afterward fell in with the terrific images of the old Latin hymn, when he composed his own “Requiem,” in writing a Requiem to order for another. In these two works the life and genius of Mozart found their highest expression. “Don Juan” and the “Requiem,” in all their contrast, are alike true to the very texture and temper of the man. “Don Juan,” written in the hey-day of his genial faculties, in his hour and scene of greatest outward success, in the city of Prague, where he was understood and loved as nowhere else, surrounded by devoted friends, and with an orchestra and troup of singers worthy to be his interpreters, represents his sunny side, his keen sensibility to all refined delights of sense and soul, and his great faith in joy, in ecstasy, in all material and sensual harmonies. The “Requiem” bears to “Don Juan,” as a whole, the same relation that the last scene of that opera bears to the preceding parts; it expresses the religious awe and mystery of his soul, his singular presentiment of death, his constant feeling of the Infinite. The opera, in its last scene, rises to a sphere of music kindred with the “Requiem;” there vibrated the same deep chords of his nature. It was the very subject of all others for him to pour the whole warm life-tide of his soul and music into, and thus lift up and animate a poor old literal fiction, that somehow strangely kept its hold upon the popular mind, with all its weight of grotesqueness, extravagance, vulgarity and tom-foolery, into a vivid drama of the whole impetuous, bewildered, punished, yet far-hoping and indomitable experiment of human life.