Johnson may be said to occupy the central place in that highly characteristic school of didactic poetry which was originated by Pope and completed by Goldsmith. The essence of Pope's didactic compositions is personal satire. It is true that he specially prides himself on being the champion of virtue and the great promoter of moral truth. But the virtue which he had invariably before his imagination was his own, and throughout his Imitations of Horace morality is always exalted in the person of the poet, and always seems so be endangered by the wicked virulence of his private enemies. In consequence of their intense personality, Pope's didactic poems fail in point of poetical design. In the Essay on Man the subject-matter is Bolingbroke's rather than Pope's, and the conduct of the argument is extraordinarily confused; while in the Moral Essays and Satires, what really pleases is the beauty of detail, the terse epigrams, the brilliant images, and above all the matchless portraiture of particular characters. The great beauty of Goldsmith's poems, on the other hand, lies in the justness of their design, the relation of the means to the end, and of the parts to the whole. He relies hardly at all on personal interest for his effects; but he is perhaps the most persuasive of all didactic poets, from the extraordinary art which he possesses of enlisting simple and universal feelings in behalf of the moral principle which he seeks to establish.
Johnson unites in his own style many of the opposite excellences exhibited by his predecessor and his friend. It was impossible that the bias of his strong character should be altogether concealed in his verse, and London in particular appears to have been largely inspired by personal motives like those which suggested to Pope his Imitations of Horace. But the different genius of the two poets is seen in the selection of their respective originals. Pope was struck by the many superficial points of resemblance between himself and the lively egotistical Horace, and seized eagerly on the opportunity of presenting his own virtues, friendships, and enmities to the public under a transparent veil of imitation. Johnson, on the contrary, who, as an unknown writer, could not hope to interest the public in his personal concerns, chose a general theme, and imitated the satirist whose denunciations of Roman vice offered, in many respects, an apt parallel to the manners of his own age. London is marked by genuine public spirit; at the same time we see quite as much of the man as of the moralist in the poet's characteristic allusions so the penalties of poverty, his antipathy to the Whigs, and his dislike of foreigners. The story that "Thales" was meant for Savage, and that the occasion of the poem was the departure of the latter from London after his trial, is confuted by dates, but we may be sure that the poem gives us a real representation of Johnson's feelings as a struggling author and a political partisan.
The Vanity of Human Wishes marks a calmer and more prosperous epoch in the poet's life, and its philosophical generalising spirit is an anticipation of Goldsmith's Traveller. Johnson was now relieved from the immediate pressure of want; and in his second limitation he takes a wider survey of mankind; he suppresses all personal satire, and fetches the illustrations of his argument from distant times. The style of this poem is also completely different from that of London: in the latter he is ardent, animated, and colloquial, while in the Vanity of Human Wishes he speaks with the gravity of a moralist, making his periods swelling and sonorous, balancing his verses against each other, and equalling Pope himself in the condensation of his language. Nevertheless, the whole spirit of the composition, though professedly an imitation, is highly characteristic of the man: we see in it the melancholy gloom that darkened all his view of human existence, while at the same time the noble lines of the conclusion recall the language of those touching fragments of prayer which Boswell discovered among his papers and has preserved in his Life.
His Prologues are of the highest excellence; indeed it may be confidently affirmed that he is the best writer of prologues in the language. No man was ever so well qualified to strike that just mean between respectfulness and authority which such addresses to the public require. His sound critical power and elevated feeling are well exemplified in the Prologue spoken at the opening of Drury Lane Theatre; and there is true greatness of spirit in his prologue to Comus, in which he claims the liberality of the audience for Milton's granddaughter as a tardy redress for the injustice shown by the nation to the genius of the poet himself. His admirable independence of character is perhaps even better seen in the Prologue to A Word to the Wise, a play which at its first exhibition was damned in consequence of political prejudices against the author, but was revived after his death. Nothing can be better than the dignity with which Johnson, in this address, while recognising the judicial authority of the audience, indirectly reproves them for their previous disregard of the laws of humanity by which all their verdicts ought to be determined.