At my return to Paris, I learned the agreeable news that Diderot was released from the dungeon, and that he had on his parole the castle and park of Vincennes for a prison, with permission to see his friends.  How painful was it to me not to be able instantly to fly to him!  But I was detained two or three days at Madam Dupin’s by indispensable business.  After ages of impatience, I flew to the arms of my friend.  He was not alone:  D’ Alembert and the treasurer of the Sainte Chapelle were with him.  As I entered I saw nobody but himself, I made but one step, one cry; I riveted my face to his:  I pressed him in my arms, without speaking to him, except by tears and sighs:  I stifled him with my affection and joy.  The first thing he did, after quitting my arms, was to turn himself towards the ecclesiastic, and say:  “You see, sir, how much I am beloved by my friends.”  My emotion was so great, that it was then impossible for me to reflect upon this manner of turning it to advantage; but I have since thought that, had I been in the place of Diderot, the idea he manifested would not have been the first that would have occurred to me.

I found him much affected by his imprisonment.  The dungeon had made a terrible impression upon his mind, and, although he was very agreeably situated in the castle, and at liberty to, walk where he pleased in the park, which was not inclosed even by a wall, he wanted the society of his friends to prevent him from yielding to melancholy.  As I was the person most concerned for his sufferings, I imagined I should also be the friend, the sight of whom would give him consolation; on which account, notwithstanding very pressing occupations, I went every two days at farthest, either alone, or accompanied by his wife, to pass the afternoon with him.

The heat of the summer was this year (1749) excessive.  Vincennes is two leagues from Paris.  The state of my finances not permitting me to pay for hackney coaches, at two o’clock in the afternoon, I went on foot, when alone, and walked as fast as possible, that I might arrive the sooner.  The trees by the side of the road, always lopped, according to the custom of the country, afforded but little shade, and exhausted by fatigue, I frequently threw myself on the ground, being unable to proceed any further.  I thought a book in my hand might make me moderate my pace.  One day I took the Mercure de France, and as I walked and read, I came to the following question proposed by the academy of Dijon, for the premium of the ensuing year, ’Has the progress of sciences and arts contributed to corrupt or purify morals?’