the good fortune of having made your acquaintance

At nine o'clock D'Artagnan was at the Hotel des Gardes; he found Planchet all ready. The fourth horse had arrived.
Planchet was armed with his musketoon and a pistol. D'Artagnan had his sword and placed two pistols in his belt; then both mounted and departed quietly. It was quite dark, and no one saw them go out. Planchet took place behind his master, and kept at a distance of ten paces from him.
D'Artagnan crossed the quays, went out by the gate of La Conference and followed the road, much more beautiful then than it is now, which leads to St. Cloud.
As long as he was in the city, Planchet kept at the respectful distance he had imposed upon himself; but as soon as the road began to be more lonely and dark, he drew softly nearer, so that when they entered the Bois de Boulogne he found himself riding quite naturally side by side with his master. In fact, we must not dissemble that the oscillation of the tall trees and the reflection of the moon in the dark underwood gave him serious uneasiness. D'Artagnan could not help perceiving that something more than usual was passing in the mind of his lackey and said, "Well, Monsieur Planchet, what is the matter with us now? M. Bonacieux was at his door. D'Artagnan's intention was to go out without speaking to the worthy mercer; but the latter made so polite and friendly a salutation that his tenant felt obliged, not only to stop, but to enter into conversation with him.
Besides, how is it possible to avoid a little condescension toward a husband whose pretty wife has appointed a meeting with you that same evening at St. Cloud, opposite D'Estrees's pavilion? D'Artagnan approached him with the most amiable air he could assume.
The conversation naturally fell upon the incarceration of the poor man. M. Bonacieux, who was ignorant that D'Artagnan had overheard his conversation with the stranger of Meung, related to his young tenant the persecutions of that monster, M. de Laffemas, whom he never ceased to designate, during his account, by the title of the "cardinal's executioner," and expatiated at great length upon the Bastille, the bolts, the wickets, the dungeons, the gratings, the instruments of torture.
D'Artagnan listened to him with exemplary complaisance, and when he had finished said, "And Madame Bonacieux, do you know who carried her off?--For I do not forget that I owe to that unpleasant circumstance the good fortune of having made your acquaintance."