But the way to Immortality is through the Gate of the Grave. So in Plate 15 we have the picture of Death's Door, to which our traveller has arrived at last. This early design embodying Blake's favourite conception was destined to be enlarged and sublimed into one of the most magnificent inventions of Christian Art. This is the first hint of the perfect final work, and on that account, as well as for its own intrinsic significance here, of the greatest interest. Death's Door being opened, the Worm is seen at work in Plate 16. Who shall say how Blake has contrived to make the pale, hooded woman under the tree-roots so symbolic an image of the Worm? There is that about her at which the recoiling flesh shudders and sickens. [Illustration: THE DELUGE From W. B. Scott's Etching of Blake's undated Indian Ink Drawing, by kind permission of Messrs. Chatto and Windus] Yet here, below the dim, twisted roots of the Tree of Physical Being, whence the embryo Man was plucked like a mandrake, is the house of the worm. "I have said to the worm, thou art my mother and my sister," quotes Blake enigmatically, beneath this leprous dream of mortality. But the enigma has a solution, for the worm at least destroys that body of generative and divided nature to which it is itself so nearly akin, and which has cramped and imprisoned eternal Man while on earth. So that we may be grateful to the worm in the end, for Weaving to dreams the sexual strife, And weeping over the web of life. I have quoted an illuminating phrase here and there from the lines which Blake wrote and called the Keys of the Gates of Paradise. These, however, are but fugitive hints and thoughts suggested by the plates, and not in any real sense "keys" at all. Blake leaves each man to unlock the innermost mystery of those designs for himself. They are steeped all through in his own peculiar hues of thought, subjective to the very verge of the subjectivity allowable to art, but each of them exhibits that pictorial sense without which, however poetical and rare the meaning expressed, they could have no _raison d'etre_--no artistic right to exist. They induce the mood which assists us to their sympathetic comprehension. After the "Gates of Paradise," Blake began the production of the London "Prophetic Books," but we will consider these in the next chapter, and will conclude this early phase of Blake's work in book making by the consideration of the "Songs of Experience," which appeared in 1794--five years later than the "Songs of Innocence."