THE FAMILIAR phrase from Wordsworth's 1802 Preface which describes the poet as 'the rock of defence of human nature' has only acquired its full meaning today. At the time he wrote, when the long war had just been resumed against France and against what Wordsworth now judged to be tyranny, this claim must have seemed to many romantic in the extreme. After a hundred and seventy-five years we have learned its truth. Poetry-the most responsible use of language, depending on its past achievements and leading it to new insight-poetry in this widest sense can speak for, can bring to mind, can show as inviolable those qualities that civilization must uphold if it is not itself to collapse. The twentieth-century poet has had to face more exacting demands upon his moral sensibility than his predecessors in the last great period of poetic discovery-Wordsworth's own. It seems likely that the generation born around the year 1890 will be recognized, in the persons of at least a dozen poets, as more significant for humanity even than the generation that produced Wordsworth. Neither he, nor Blake, nor Coleridge can be said to have passed the very difficult test proposed by Ezra Pound in 1918 (with his customary over-emphasis): 'it is a disgraceful thing for a man's work not to show steady growth and increasing fineness from first to last'. The last phase of these poets is one of frustration or decline. There are, of course, fewer twentieth-century poets (among the leaders) who lived ...