Small as is the difference of principle between the later Norman vaulting and that under consideration, the impression produced upon the mind is entirely changed. The one suggests weight and pressure systematically met and resisted; in the other those forces appear to have vanished; and the effect suggested is rather a shooting boldly upwards, like the growth of a tree, than any downward pressure towards the earth. True it is that, in the decorative treatment, a colonnette is placed under every rib or group of ribs as its artistic support; yet, in its effect upon the imagination, the action is reversed. It is not the column bearing the weight of the arched ribs, but the latter springing vigorously upward from the column. Who, while viewing a stately tree in the pride of its growth, ever thinks of its _weight_, or of the pressure of its boughs upon the stem? It is with its _upward soaring_ that the mind becomes impressed; and just so it is with the interior of a Gothic cathedral. The perfection with which all physical forces are met has to the mind the effect, not merely of having annihilated, but of having actually _reversed_ them. So that upward striving, stately growth, and heavenward aspiration are the ideas customarily suggested as illustrating the impressions produced. The lofty avenue, with its intersecting branches, has become the chosen similitude to which it is popularly likened, and it has been universally received as the form of architecture most expressive of the heavenward soarings of our religion. No one who contemplates our glorious Abbey Church of Westminster, and lays his soul open to its inspiration, can fail to feel sentiments in harmony with those suggested by the cognisance of its saintly founder--selected as if in anticipation of its future glories--the symbol of our religion surrounded by martlets, whose feet are erased in token that they have lost all tendency to rest on earth, but, like the aspirations of Christian worship, ever mounting on the wing towards the supreme object of adoration, and “Flying up to Heaven gate ascend, Bear on their wings and in their notes His praise.” LECTURE XV. The Principles of Vaulting--_continued_.