In the evening to the Opera, in the box of the Swedish Minister. ‘LesMystères d’Isis’. The music is really beautiful, by Mozart; but all music becomes nearly alike by the manner in which they sing it, except just the two or three airs given by Laÿs. ‘The Mystères d’Isis’ is remarkable, even here, for its decorations and coup de théâtre. A view of Tartarus upon one side of the stage, and the Elysian Fields upon the other, showed in succession to the hero; admirable tableaux. The last scene, of a vast palace (I know not where) where the hero (I know not who) is rewarded with the hand of his mistress, very good, but not sufficiently lighted. This, I understand, always happens after the first three or four representations of a new piece; they economise upon the lights and so spoil a part of the effect.