The volume is not co-extensive with the work of the period. The third and fourth cantos of _Childe Harold_ (1816-1817), the first five cantos of _Don Juan_ (1818, 1819, 1820), _Sardanapalus_, _The Two Foscari_, _Cain_, and _Heaven and Earth_ (1821), form parts of other volumes, but, in spite of these notable exceptions, the fourth volume contains the work of the poet's maturity, which is and must ever remain famous. Byron was not content to write on one kind of subject, or to confine himself to one branch or species of poetry. He tracked the footsteps now of this master poet, now of another, far outstripping some of his models; soon spent in the pursuit of others. Even in his own lifetime, and in the heyday of his fame, his friendliest critics, who applauded him to the echo, perceived that the "manifold motions" of his versatile and unsleeping talent were not always sanctioned or blessed by his genius. Hence the unevenness of his work, the different values of this or that poem. But, even so, in width of compass, in variety of style, and in measure of success, his achievement was unparalleled. Take such poems as _Manfred_ or _Mazeppa_, which have left their mark on the literature of Europe; as _Beppo_, the _avant courrier_ of _Don Juan_, or the "inimitable" _Vision of Judgment_, which the "hungry generations" have not trodden down or despoiled of its freshness. Not one of these poems suggests or resembles the other, but each has its crowd of associations, a history and almost a literature of its own. The whole of this volume was written on foreign soil, in Switzerland or Italy, and, putting aside _The Dream_, _The Monody on the Death of Sheridan_, _The Irish Avatar_, and _The Blues_, the places, the persons and events, the _matériel_ of the volume as a whole, to say nothing of the style and metre of the poems, are derived from the history and the literature of Switzerland and Southern Europe. An unwilling, at times a vindictive exile, he did more than any other poet or writer of his age to familiarize his own countrymen with the scenery, the art and letters of the Continent, and, conversely, to make the existence of English literature, or, at least, the writings of one Englishman, known to Frenchmen and Italians; to the Teuton and the Slav. If he "taught us little" as prophet or moralist; as a guide to knowledge; as an educator of the general reader--"your British blackguard," as he was pleased to call him--his teaching and influence were "in widest commonalty spread."