I sent the other day a cargo of French dulness to my lord lieutenant. My lady Bolingbroke has taken upon herself to send you one copy of the Henriade. She is desirous to do that honour to my book; and I hope the merit of being presented to you by her hands, will be a commendation to it. However, if she has not done it already, I desire you to take one of the cargo, which is now at my lord lieutenant’s. I wish you a good hearing; if you have got it, you want nothing. I have not seen Mr. Pope this winter; but I have seen the third volume of the Miscellanea; and the more I read your works, the more I am ashamed of mine. I am, with respect, esteem, and gratitude, sir, your most humble and most obedient servant,
John Nichols (ed) 1801 The Works of the Rev. Jonathan Swift, DD, Dean of St Patricks Dublin, arranged by Thomas Sheridan, Volume 12, London, p. 269.
Though we don’t know exactly when they met or how well they knew each other, Voltaire and Swift were definitely acquainted. Voltaire wrote letters of introduction for Swift dated 14-16 June 1727 for a projected visit to France that never took place, and also wrote two letters to Swift. The first, dated December 1727, enclosed Voltaire’s Essay upon the civil wars in France and Upon the epic poetry of the European nations. It also requested Swift’s help obtaining Irish subscribers for Voltaire’s epic poem, the/ Henriade. The second is quoted above, letting Swift know his copy of the Henriade is with the Lord Lieutenant, Lord Carteret (who was one of the subscribers that was probably recruited by Swift.) Unlike the more effusive flattery of the earlier letter “Let me indulge the satisfaction of talking of you, as posterity will do”), it contains a simpler note of praise: “the more I read your works, the more I am ashamed of mine.”
Swift’s replies to these letters do not survive, but he definitely answered them. It seems likely that he wrote an introduction to the Dublin edition of Voltaire’s Essay, and went to some lengths to collect subscribers. More on the subscriptions from Ireland is here.
Christopher Thacker suggests that Voltaire probably read Gullivers Travels (a great influence on him) and met Swift’s friends Gay and Pope in 1726, finally meeting Swift himself on Swift’s last visit to England (April to August, 1727.) Voltaire is reported as saying in 1765 he stayed in the house of Lord Peterborough for three months while Swift was there.
Christopher Thacker (1967) “Swift and Voltaire” Hermathena, No. 104, Swift Number (Spring 1967), pp. 51-66.
Dublin City Council (2017) “Swift and Voltaire” (blog 30/01/2017).