But the most interesting of their acquaintances at this time  was the Reverend W. Lisle Bowles, the poet, to whose friendship my father had been introduced by an article which he had written in the Gentleman's Magazine, in support of the poet's views on the "invariable principles of poetry," as expressed in his edition of Pope. Of Lisle Bowles and his influence, as the founder of the poetical school of the second period of the Age of Sentiment, which I have ventured to characterize as the Poetry of Taste, I have spoken in the first chapter of this work. My father had indeed intended to write his life, and has left behind him copious collections with this view derived from Mr. Bowles's correspondence, to which access was permitted to him through the late Dr. Bowles, of Stanton Lacy; but the project fell through.
It might have been said of Bowles, as Lord Thurlow said of Crabbe, "He was as like Parson Adams as twelve to the dozen." While of a tender and sensitive nature, and the parent, as I have said, of the poetical school of tasteful sensibility, he was a man of vigorous and independent judgment, great critical discrimination, and upon questions of argument feared no man living, laying about him in controversial conflict, when it presented itself, with all the readiness and aptitude to the use of his weapons of the admirable athlete and sound divine with whom I have ventured to compare him.
The particular controversy now in question, into which my father had thrown himself with corresponding ardour and stomach for fight, and which is, I think, of general and permanent critical interest, arose in this wise:
Mr. Bowles had produced for the booksellers in the year 1806 an edition of the works of Pope, with variorum notes, in no less than ten volumes. He had concluded this work with some observations on the poetical character and status of Pope, in which he referred to the outcry which had attended Warton's essay on the life and genius of this writer, as though Warton had intended to deny to Pope his just measure of fame as a poet; and he endeavoured to lay down some principles of poetical criticism as a basis for a judgment on the subject on his own part.
In doing so, he presumed that it would be readily granted "that all images drawn from what is beautiful or sublime in the works of Nature are more beautiful and sublime than any images drawn from Art;" and that they are therefore per se more poetical. Ensuing on this proposition, he went on to the observation that, in like manner, "those passions of the human heart which belong to Nature in general, are per se more adapted to the higher species of poetry than those which are derived from incidental and transient manners."
Founding on this line of argument, and making allowance for the qualities displayed in the Epistle of Eloisa, which he declares his conviction to be infinitely superior to everything of the kind, ancient or modern, he proceeds to affirm that while one of the first poets that England and the polished literature of a polished era can boast, Pope does not stand pre-eminent in the highest sense of the definition of a poet.
To these propositions Mr. Campbell the poet, in his essay on English Poetry, prefixed to his Specimens of the British Poets, took serious exception, claiming that the faculty by which a poet luminously describes objects of Art is essentially the same faculty as that which enables him to be a faithful describer of simple Nature. In the second place, that Nature and Art are to a greater degree relative terms, in poetical description, than is generally recollected; and thirdly, that artificial objects and manners are of so much importance in fiction as to make the exquisite description of them no less characteristic of genius than the description of simple physical appearances.
To this criticism, which was supported by a variety of acute and interesting arguments, Mr. Bowles, in the year 1819, rejoined in a pamphlet on The Invariable Principles of Poetry, written in the form of a letter to Mr. Campbell, in which, with much grace, good humour, and courtesy, he reviewed his original arguments and those of his brother bard, replying to the latter with great force, both in principle and detail; and while disclaiming the smallest desire to underrate the poetry of Pope, maintaining with firmness and dignity the position already assumed.
For these opinions Bowles was attacked in various quarters with much virulence, as was the fashion of that day. It was as an answer to this pamphlet that Lord Byron's well-known letter to Bowles was written. It contributed fun and humour to the controversy, but added, I think, little to the arguments.
The result of this controversy upon the mind of the impartial reader will perhaps be to recall and confirm the observation of Johnson, that it is much more easy to determine what is not poetry than to define what is.