In their keeping he found a part of his papers, plans and projects, memorials and dissertations. He sent “a basketful” of these to Marshal de Noailles, begging him to continue to honour him with his protection, and imparting to him “four great discoveries he had just made; first, the true cause of the tides; secondly, the true cause of mountains, but for which the globe would be brought to a standstill and become speedily vitrified; thirdly, the cause of the ceaseless turning of the globe; fourthly, the cause of the saltness of sea-water.” He wrote also to the Duke de Choiseul, minister of war, in order to obtain a reward for his military scheme; he wrote making overtures of peace to Sartine: in return for an advance of 10,000 crowns of the 150,000 livres due to him, he would overlook the past: “I was resolved,” he says, “to stake all on one cast.” In reply, he received a letter naming a house where he would find 1200 livres obtained for him by Dr. Quesnay. He proceeded to the address indicated—and was there captured.
He was at once taken back to Vincennes. He declares that he was about to be set at liberty at the moment of his escape: and now a new detention was commencing. We shall not relate in detail the life he was now to lead. Materially he continued to be well treated, but his mind became affected, his rages became more and more violent, reaching at last paroxysms of fury. Here are some extracts from letters and memorials sent to Sartine: “By all the devils, this is coming it too strong. It is true, sir, that I’d defy the blackest devils in all hell to teach you anything in the way of cruelty; and that’s but poor praise for you.” He writes on another occasion: “The crime of every one of us is to have seen through your villainies: we are to perish, are we? how delighted you would be if some one told you that we had all strangled ourselves in our cells!” Danry reminds the lieutenant of police of the tortures of Enguerrand de Marigni, adding: “Remember that more than a thousand wretches have been broken in the Place de Grève who had not committed the hundredth part of your crimes.”... “Not a single person would be astonished to see you flayed alive, your skin tanned, and your carcase thrown into the gutters for the dogs to eat.”... “But Monsieur laughs at everything, Monsieur fears neither God, nor king, nor devil, Monsieur swills down his crimes like buttermilk!”
In prison Latude wrote memoirs which he filled with calumnies on the ministers and the court. These memoirs are composed in the most dramatic style, with an inimitable accent of sincerity. It was known that the prisoner found a thousand means of sending them outside the walls, and it was feared that they might be circulated among the populace, whose minds—the year is 1775—were beginning to ferment. Latude had just been flung into a cell in consequence of a fresh outbreak against his jailers. “On March 19, 1775, the king’s lieutenant entered, accompanied by the major and three warders, and said to me: ‘I have obtained leave to let you out of the cell, but on one condition: that you hand over your papers.’
“‘Hand over my papers! I tell you, sir, I’d rather be done to death in this cell than show the white feather so!’
“‘Your trunk is upstairs in your room: I’ve only to say the word and the seals would be broken and your papers taken out.’
“I replied: ‘Sir, justice has formalities to which you are bound to conform, and you are not allowed to commit such outrages.’
“He took five or six steps out of the cell, and as I did not call him back, he came back himself and said: ‘Just hand them to me for ten days to examine them, and I give you my word of honour that at the end of that time I will have them returned to your room.’
“I replied: ‘I will not let you have them for two hours even.’
“‘All right,’ he said; ‘as you won’t entrust them to me, you have only to stay where you are.’”
Latude relates in his Memoirs with great indignation the story of a flute he had made, on which he used to play, his sole diversion during the long hours of solitude; his jailers had the barbarity to take it from him. The governor of the fortress, out of compassion, offered to restore it. “But it will only be on condition that you play by day only, and not at night.” At this stipulation, writes Latude in his Rêveries, “I could not refrain from bantering him, saying, ‘Why, don’t you know, sir, that forbidding a thing is just the way to make me eager for it?’”