(1) They exploited the aesthetic values to be had by knowledge. They pursued erudition and built their poetry upon erudition, not in the didactic way of the Augustans, but as a mine of poetic material and suggestion. Far more truly than Wordsworth's this poetry could claim to be the impassioned expression which is in the face of science; for Wordsworth's knowledge is a mystic insight wholly estranged from erudition; his celandine, his White Doe, belong to no fauna or flora. When Leconte de Lisle, on the other hand, paints the albatross of the southern sea or the condor of the Andes, the eye of a passionate explorer and observer has gone to the making of their exotic sublimity. The strange regions of humanity, too, newly disclosed by comparative religion and mythology, he explores with cosmopolitan impartiality and imaginative penetration; carving, as in marble, the tragedy of Hjalmar's heart and Angentyr's sword, of Cain's doom, and Erinnyes never, like those of Aeschylus, appeased. The Romantics had loved to play with exotic suggestions; but the East of Hugo's _Orientales_ or Moore's _Lalla Rookh_ is merely a veneer; the poet of _Qain_ has heard the wild asses cry and seen the Syrian sun descend into the golden foam. In the three commanding poets of our English mid-century, learning becomes no less evidently poetry's honoured and indispensable ally. Tennyson studies nature like a naturalist, not like a mystic, and finds felicities of phrase poised, as it were, upon delicate observation. Man, too, in Browning, loses the vague aureole of Shelleyan humanity, and becomes the Italian of the Renascence or the Arab doctor or the German musician, all alive but in their habits as they lived, and fashioned in a brain fed, like no other, on the Book of the histories of Souls. Matthew Arnold more distinctively than either, and both for better and for worse, was the scholar-poet; among other things he was, with Heredia and Carducci, a master of the poetry of critical portraiture, which focusses in a few lines (_Sophocles_, _Rahel_, _Heine_, _Obermann Once More_) the meaning of a great career or of a complex age.