Matthew Arnold,
preface to his edition of Byron's Poems (1881)
 

***In spite of his prodigious vogue, Byron has never yet, perhaps, had the serious admiration which he deserves.***Even of his passionate admirers, how many never got beyond the theatrical Byron, from whom they caught the fashion of deranging their hair, or of knotting their neck-handkerchief, or of leaving their shirt-collar unbuttoned; how few profoundly felt his vital influence, the influence of his splendid and imperishable excellence of sincerity and strength!
    His own aristocratic class, whose cynical make-believe drove him to fury; the great middle-class, on whose impregnable Philistinism he shattered himself to pieces, - how little have either of these felt Byron's vital influence!  As the inevitable break-up of the old order comes, as the English middle-class slowly awakens from its intellectual sleep of two centuries, as our actual present world, to which this sleep has condemned us, shows itself more clearly, - our world of an aristocracy materialised and null, a middle-class purblind and hideous, a lower class crude and brutal, - we shall turn our eyes again, and to more purpose, upon this passionate and dauntless soldier of a forlorn hope, who, ignorant of the future and unconsoled by its promises, nevertheless waged against the conservation of the old impossible world so fiery battle; waged it till he fell, - waged it with such splendid and imperishable excellence of sincerity and strength.
    Wordsworth's value is of another kind.  Wordsworth has an insight into permanent sources of joy and consolation for mankind which Byron has not; his poetry gives us more which we may rest upon than Byron's, - more which we can rest upon now, and which men may rest upon always.  I place Wordsworth's poetry, therefore, above Byron's on the whole, although in some points he was greatly Byron's inferior, and although Byron's poetry will always, probably, find more readers than Wordsworth's, and will give pleasure more easily.  But these two, Wordsworth and Byron, stand, it seems to me, first and pre-eminent in actual performance, a glorious pair, among the English poets of this century.  Keats had probably, indeed, a more consummate poetic gift than either of them; but he died having produced too little and being as yet too immature to rival them.  I for my part can never even think of equaling with them any other of their contemporaries; - either Coleridge, poet and philosopher wrecked in a mist of opium; or Shelley, beautiful and ineffectual angel, beating in the void his luminous wings in vain.  Wordsworth and Byron stand out by themselves.  When the year 1900 is turned, and our nation comes to recount her poetic glories in the century which has just then ended, the first names with her will be these.
 

This famous and oft-quoted passage is also included in Arnold's justly-celebrated Essays in Criticism, Second Series.