Gabriel Ferry states that Balzac first saw Madame Hanska’s face at a window, and the Princess Radziwill says that Balzac went to the hotel to meet her aunt.  It is to be noted that the year 1834 is that in which Balzac and Madame Hanska were in Geneva together.

The Villa Diodati, noted for having been inhabited by Lord Byron, is situated on Lake Geneva, at Cologny, not far from Pre Leveque,[*] where M. de Hanski and his family resided in the maison Mirabaud-Amat.

[*] Balzac preserved a remembrance of the happy days he had spent with
    Madame Hanska at Pre-Leveque, Lake Geneva, by dating La Duchesse
    de Langeais, January 26, 1834, Pre-Leveque.

There are numerous allusions to Diodati in Balzac’s correspondence, from which one would judge that he had some very unhappy associations with Madame de Castries, and some very happy ones with Madame Hanska in connection with Diodati: 

“When I want to give myself a magnificent fete, I close my eyes, lie down on one of my sofas, . . . and recall that good day at Diodati which effaced a thousand pangs I had felt there a year before.  You have made me know the difference between a true affection and a simulated one, and for a heart as childlike as mine, there is cause there for an eternal gratitude. . . .  When some thought saddens me, then I have recourse to you; . . .  I see again Diodati, I stretch myself on the good sofa of the Maison Mirabaud. . . .  Diodati, that image of a happy life, reappears like a star for a moment clouded, and I began to laugh, as you know I can laugh.  I say to myself that so much work will have its recompense, and that I shall have, like Lord Byron, my Diodati.  I sing in my bad voice:  ‘Diodati, Diodati!’”

Another excerpt shows that Balzac had in mind his own life in connection with Madame Hanska’s in writing Albert Savarus: 

“. . .  It is six o’clock in the morning, I have interrupted myself to think of you, reminded of you by Switzerland where I have placed the scene of Albert Savarus.—­Lovers in Switzerland,—­for me, it is the image of happiness.  I do not wish to place the Princess Gandolphini in the maison Mirabaud, for there are people in the world who would make a crime of it for us.  This Princess is a foreigner, an Italian, loved by Savarus.”

Many of Balzac’s traits are seen in Albert Savarus.  Like Balzac, Albert Savarus was defeated in politics, but hoped for election; was a lawyer, expected to rise to fame, and was about three years older than the woman he loved.  Like Madame Hanska, the Duchesse d’Argaiolo, known as the Princess Gandolphini, was beautiful, noble, a foreigner, and married to a man very rich and much older than she, who was not companionable.  It was on December 26 that Albert Savarus arrived at the Villa on Lake Geneva to visit his princes, while Balzac arrived December 25 to visit Madame Hanska at her Villa there.  The two lovers spent the winter together, and in the spring, the Duc d’Argaiolo (Prince Gandolphini) and his wife went to Naples, and Albert Savarus (Rodolphe) returned to Paris, just as M. de Hanski took his family to Italy in the spring, while Balzac returned to Paris.