John, a celebrated critic, was the son of a respectable tradesman in London, and born in the year 1657. He received the first branches of education at the great school in Harrow on the Hill, where he commenced acquaintance and intimacy with many young noblemen and gentlemen, who afterwards made a considerable figure in public affairs, by which means he laid the foundation of a very strong and extensive interest, which, but for his own fault, might have been of infinite use to him in his future life. From Harrow he went to Caius-College, Cambridge, where, as soon as he was of proper standing, he took the degree of bachelor of arts. When he quitted the university, he made the tour of Europe, in the course of which he conceived such a detestation of despotism; as confirmed him still more in those Whig principles which he had from his infancy imbibed.

On his return to England, he became early acquainted with Dryden, Wycherly, Congreve, and Southerne, whose conversation inspiring him with a passion for poetry, and a contempt for every attainment that had not in it something of the belles lettres, diverted him from the acquisition of any profitable art, or the exercise of any profession. This, to a man who had not an independent income, was undoubtedly a misfortune. However, his zeal for the Protestant succession having recommended him to the patronage of the Duke of Marlborough, that nobleman procured him a place in the customs worth L120 per annum; which he enjoyed for some years, till, from profuseness and want of economy, he was reduced to the necessity of disposing of it to satisfy some very pressing demands. By the advice of Lord Halifax, however, he reserved to himself, in the sale of it, an annuity for a term of years; which term he outlived, and hence, in the decline of his life, he was reduced to extreme necessity.

Theobald Cibber relates an anecdote of him, which we cannot avoid repeating, as it is not only highly characteristic of the man whose affairs we are now considering, but also a striking and melancholy instance, among thousands, of the distressful predicaments into which men of genius plunge themselves, by paying too slight an attention to the common concerns of life, and their own most important interests. "After that he was worn out with age and poverty, he resided within the verge of the court, to prevent danger from his creditors. One Saturday night he happened to saunter to a public house, which in a short time he discovered to be without the verge. He was sitting in an open drinking room, when a man of a suspicious appearance happened to come in. There was something about the man which denoted to Dennis that he was a bailiff. This struck him with a panic; he was afraid his liberty was at an end; he sat in the utmost solicitude, but did not offer to stir lest he should be seized upon. After an hour or two had passed in this painful anxiety, at last the clock struck twelve, when Dennis, in an ecstacy, cried out, addressing himself to the suspected person, 'Now, Sir, bailiff or no bailiff, I don't care a farthing for you; you have no power now.' The man was astonished at his behaviour; and when it was explained to him, was so much affronted with the suspicion, that had not Dennis found his protection in age, he would probably have smarted for his mistaken opinion." This presents a strong picture of the effects of fear and apprehension in a temper naturally so timorous and jealous as was that of Dennis. The following is a still more whimsical instance: In 1704 appeared his favourite tragedy Liberty Asserted; in which there were so many strokes against the French nation, that he thought they were never to be forgiven. He had worked himself into a persuasion that the king of France would insist on his being delivered up before consenting to conclude a peace; and, full of this idea of his own importance, when the congress was held at Utrecht, he is said to have waited on his patron, the Duke of Marlborough, in order to desire that no such article might be stipulated. The duke told him that he had really no interest then with the ministry; but that he had made no such provision for his own security, though he could not help thinking he had done the French as much injury as Dennis himself. Another story relating to this affair is, that being at a gentleman's house on the coast of Sussex, and walking one day on the sea-shore, he saw a ship sailing, as he fancied, towards him. He instantly set out for London, in the fancy that he was betrayed; and congratulating himself upon his escape, gave out that his friend had decoyed him down to his house in order to surrender him up to the French.

Dennis, partly through a natural peevishness and petulance of temper, and partly perhaps for the sake of procuring the means of subsistence, was continually engaged in controversy with his contemporaries, whom he ever treated with the utmost severity; and though many of his observations were judicious, yet he usually conveyed them in language so scurrilous and abusive as destroyed their intended effect; and as his attacks were almost always on persons of abilities superior to himself, as Addison, Steele, and Pope, their replies usually turned the popular opinion so greatly against him, that, by irritating his testy temper the more, it rendered him a perpetual torment to himself; till at Denomination-length, after a long life of vicissitudes, disappointments, and turmoils, rendered wretched by indiscretion, and hateful by malevolence, having outlived the reversion of his estate, and being reduced to distress, from which his having daily created enemies to himself had left him scarcely any hopes of relief, he was compelled to submit to the most humiliating condition that can be conceived in human life, the receiving obligations from those whom he had been continually treating ill. In the very close of his days a play was acted for his benefit at the little theatre in the Haymarket, through the united interests of Thomson, Mallet, and Pope; the last of whom, notwithstanding the gross manner in which Dennis had on many occasions used him, and the long warfare which had subsisted between them, interested himself very warmly in his behalf, and even wrote an occasional prologue to the play, which was spoken by Gibber. Not long after this, on the 6th of January 1733, the unfortunate man died, being then in the seventy-seventh-year of his age.

Dennis was certainly possessed of much erudition, and a considerable share of genius. In prose he is far from being a bad writer, where abuse or personal scurrility does not mingle itself with his language. In verse he is extremely unequal, his numbers being sometimes spirited and harmonious, and his subjects elevated and judicious, but at others flat, harsh, and puerile. As a dramatic author, he certainly deserves not to be held in any consideration. It was justly said of him by a wit, that he was the most complete instructor for a dramatic poet, since he could teach him to distinguish good plays by his precepts, and bad ones by his examples.