Voltaire was not the man to undervalue such services. His letters are full of expressions of gratitude, as delicate as they are sincere; he cast about for a means of displaying it more amply; and with many another earnest of confidence and regard, d'Argenson received the opening chapters of the "Histoire du Siècle de Louis XIV.," and with it the assurance, "I wish to please you so much; and you will see that if I do not succeed, it is not for want of working upon subjects which are dear to you."[249] D'Argenson must have been emboldened by the confidence of his friend, for soon after, Voltaire received a letter, and with it an extract of a certain manuscript from d'Argenson's own pen. The keen surprise and pleasure which attended its perusal are written in every line of Voltaire's reply:-- "My dear Sir, Providence has kept me here a day longer than we intended in order that I might receive the most pleasing letter that I have had since Madame du Châtelet has ceased to write. I have just been reading to her the extract you have been good enough to make for us from a work of which it may be said, more justly than of 'Télémaque,' that if any book could confer happiness upon mankind, it would be this.... We have not here the mere dreams of a good-hearted man, like the good Abbé de St. Pierre and M. de Fénélon; there is here something more real, and something which experience proves in the most striking manner.... Madame du Châtelet is enchanted with your plan. By this post I have received a letter from a prince, whose first minister you would be, if you had been born in his country."[250] "There is a place that one does not procure for cash down, and that I merit by the most respectful attachment and the most high esteem." The last word is significant; Voltaire was attached to his friends; his esteem was reserved for his equals. The book was kept for six weeks, when Voltaire returned by Moussinot "the best and most instructive work that I have read for twenty years.[252]... I am assured that the author of this unique work is not going to Lisbon[253] to bury his talents for guiding men and making them happy. May he remain at Paris, and may I find him again in one of those posts where, up to the present, so much harm has been done and so little good. If I had myself to choose, I swear that I would not set foot again in Paris until I saw M. d'Argenson in the place of his father, and at the head of letters.... Madame du Châtelet is as charmed as I, and will praise you to much better purpose."