On this rock, the human soul, he takes his stand, and, though all the complex waves of the tempest of nineteenth-century thought break against his feet, he remains firm. Beginning with "Sordello," it is no longer evolution as applied to every aspect of the universe but evolution as applied to the human spirit which has his chief interest. Problems growing out of the marvelous developments of such sciences as astronomy, geology, physics, chemistry or biology do not enter into the main body of the poet's thought, though there are allusions many and exact which show his familiarity with the growth of these various objective sciences during his life. During all the middle years of his poetic career the relations of the mind and the spirit seemed to fascinate Browning, especially upon the side of the problems connected with the supernatural bases of religious experience. These are the problems which grew out of that phase of scholarly advance represented by biblical criticism. Such a poem as "Saul," for example, though full of a humanity and tenderness, as well as of a sheer poetic beauty, which endear it alike to those who appreciate little more than the content of the poem, and to those whose appreciation is that of the connoisseur in poetic art, is nevertheless an interpretation of the origin of prophecy, especially of the Messianic idea, which places Browning in the van of the thought of the century on questions connected with biblical criticism. At the time when "Saul" was written, 1845, modern biblical criticism had certainly gained very little hearing in England, for even as late as 1862 Bishop Colenso's enlightened book on the Pentateuch was received, as one writer expresses it, with "almost unanimous disapprobation and widespread horror." Critics of the Bible there had been since the seventeenth century, but they had produced a confused mass of stuff in their attacks upon the authenticity of the Bible against which the orthodox apologists had succeeded in holding their own. At the end of the eighteenth and the dawn of the nineteenth century came the more systematic criticism of German scholars, echoes of whose theories found their way into England through the studies of such men as Pusey. But these, though they gave full consideration to the foremost of the German critics of the day, ranged themselves, for the most part, on the side of orthodoxy.