...It is impossible for me to describe to you how great a pleasure the acquaintance with this “God-sent one” (as some enthusiasts justly call her) has given me.  Prince Radziwitt introduced me to her, for which I feel greatly obliged to him.  Unfortunately, I profited little by her eight days’ stay with us, and I saw how she was bored by dull visits from senators, woyewods, castellans, ministers, generals, and adjutants, who only sat and stared at her while they were talking about quite indifferent things.  She receives them all very kindly, for she is so very good-natured that she cannot be unamiable to anyone.  Yesterday, when she was going to put on her bonnet previously to going to the rehearsal, she was obliged to lock the door of her room, because the servant in the ante-room could not keep back the large number of callers.  I should not have one to her if she had not sent for me, Radziwill having asked me to write out a song which he has arranged for her.  This is an Ukraine popular song ("Dumka”) with variations.  The theme and finale are beautiful, but the middle section does not please me (and it pleases Mdlle.  Sontag even less than me).  I have indeed made some alterations, but it is still good for nothing.  I am glad she leaves after to-day’s concert, because I shall pet rid of this business, and when Radziwill comes at the close of the Diet he may perhaps relinquish his variations.

Mdlle.  Sontag is not beautiful, but in the highest degree captivating; she enchants all with her voice, which indeed is not very powerful, but magnificently cultivated.  Her diminuendo is the non plus ultra that can be heard; her portamento wonderfully fine; her chromatic scales, especially toward the upper part of her voice, unrivalled.  She sang us an aria by Mercadante, very, very beautifully; the variations by Rode, especially the last roulades, more than excellently.  The variations on the Swiss theme pleased so much that, after having several times bowed her acknowledgments for the applause, she had to sing them da capo.  The same thing happened to her yesterday with the last of Rode’s variations.  She has, moreover, performed the cavatina from “Il Barbiere”, as well as several arias from “La Gazza ladra” and from “Der Freischutz”.  Well, you will hear for yourself what a difference there is between her erformances and those we have hitherto heard here.  On one occasion was with her when Soliva came with the Misses Gladkowska [the idea!] and Wolkaw, who had to sing to her his duet which concludes with the words “barbara sorte”—­you may perhaps remember it.  Miss Sontag remarked to me, in confidence, that both voices were really beautiful, but already somewhat worn, and that these ladies must change their method of singing entirely if they did not wish to run the risk of losing their voices within two years.  She said, in my presence, to Miss Wolkow that she possessed much facility and taste, but had une voix trop aigue.