All these things had prepared an unfriendly fate for Diderot when his time at last came, as it came to most of his friends.  For a month he was cut off from the outer world.  His only company was the Paradise Lost, which he happened to have in his pocket at the moment of his arrest.  He compounded an ink for himself, by scraping the slate at the side of his window, grinding it very fine, and mixing with wine in a broken glass.  A toothpick, found by happy accident in the pocket of his waistcoat, served him for pen, and the fly-leaves and margins of the Milton made a repository for his thoughts.  With a simple but very characteristic interest in others who might be as unfortunate as himself, he wrote upon the walls of his prison his short recipe for writing materials.[84] Diderot might easily have been buried here for months or even years.  But, as it happened, the governor of Vincennes was a kinsman of Voltaire’s divine Emily, the Marquise du Chatelet.  When Voltaire, who was then at Luneville, heard of Diderot’s ill-fortune, he proclaimed as usual his detestation of a land where bigots can shut up philosophers under lock and key, and as usual he at once set to work to lessen the wrong.  Madame du Chatelet was made to write to the governor, praying him to soften the imprisonment of Socrates-Diderot as much as he could.[85] It was the last of her good deeds, for she died in circumstances of grotesque tragedy in the following month (Sept. 1749), and her husband, her son, Voltaire, and Saint Lambert alternately consoled and reproached one another over her grave.  Diderot meanwhile had the benefit of her intervention.  He was transferred from the dungeon to the chateau, was allowed to wander about the park on his parole, and to receive visits from his friends.  One of the most impulsive of these friends was Jean Jacques.  Their first meeting after Diderot’s imprisonment has been, described by Rousseau himself, in terms at which the phlegmatic will smile—­not wisely, for the manner of expressing emotion, like all else, is relative.  “After three or four centuries of impatience, I flew into the arms of my friend.  O indescribable moment!  He, was not alone; D’Alembert and the treasurer of the Sainte Chapelle were with him.  As I went in, I saw no one but himself.  With a single hound and a cry, I pressed his face close to mine, I clasped him tightly in my arms, without speaking to him save by my tears and sobs; I was choking with tenderness and joy."[86] After this Rousseau used to walk over to see him two or three times a week.  It was during one of these walks on a hot summer afternoon, that he first thought of that memorable literary effort, the essay against civilisation.  He sank down at the foot of a tree, and feverishly wrote a page or two to show to his friend.  He tells us that but for Diderot’s encouragement he should hardly have executed his design.  There is a story that it was Diderot who first suggested to Rousseau to affirm that arts and sciences had corrupted