This was called 'Dr. Norris's Narrative of the Frenzy of Mr. John Dennis,' Dr. Norris being celebrated at the time as a doctor for the insane.
The whole of this transaction was discreditable in the extreme to pope. The real facts are as follows :—
Dennis had attacked the Essay on Criticism in reply to the strictures on himself therein contained. Though far from being a match for Pope in ability, he was not altogether destitute of parts, and had a gift, formidable in those days, of almost unlimited scurrility. Johnson allows that Pope showed he felt 'his force or his venom'(p. 135, 1. 15). And Pope, thus roughly handled, long meditated revenge, and did not scruple, when Addison's 'Cato' was published, to try and make of his friend a tool to be used against his enemy. He accordingly went to Lintot and persuaded him to engage Dennis to attack the Cato, of whose, success Pope had become jealous. There was here a triple scheme; to disparage the Cato, to provide for Dennis a severe chastisement at the hands of so able a man as Addison, and to give himself an opportunity of an assault on Dennis, without appearing to have any personal feeling in the matter. The 'cant of sensibility' alluded to in the letter from Pope to Addison on 20/7/1713, was thus worse than cant; it was falsehood. And its object was to deceive the public, for Pope must have known it could not deceive Addison for long. It is pleasing to think how the whole scheme collapsed. Dennis exposed him in 1728, in his 'Remarks on the Rape of the Lock,' and again in 1729, in his 'Remarks on the Dunciad,' and on neither occasion did Pope venture a reply. Cf. p. 173, l. 3. The truth must have reached the ears of Addison, and was enough to justify any hostility he may have felt for Pope. And Addison, instead of attacking Dennis, disclaimed to him the whole affair.