Letters,(E 730) [To Thomas Butts] Felpham July 6. 1803 ... "This Poem shall by Divine Assistance be progressively Printed & Ornamented with Prints & given to the Public--But of this work I take care to say little to Mr H. since he is as much averse to my poetry as he is to a Chapter in the Bible He knows that I have writ it for I have shewn it to him & he had read Part by his own desire & has lookd with sufficient contempt to enhance my opinion of it. But I do not wish to irritate by seeming too obstinate in Poetic pursuits But if all the World should set their faces against This. I have Orders to set my face like a flint. Ezekiel iii C 9 v. against their faces & my forehead against their foreheads"
 Behold, I have made thy face strong against their faces, and thy forehead strong against their foreheads.
 As an adamant harder than flint have I made thy forehead: fear them not, neither be dismayed at their looks, though they be a rebellious house.
 Moreover he said unto me, Son of man, all my words that I shall speak unto thee receive in thine heart, and hear with thine ears.
 And go, get thee to them of the captivity, unto the children of thy people, and speak unto them, and tell them, Thus saith the Lord GOD; whether they will hear, or whether they will forbear.
 Then the spirit took me up, and I heard behind me a voice of a great rushing, saying, Blessed be the glory of the LORD from his place.
 I heard also the noise of the wings of the living creatures that touched one another, and the noise of the wheels over against them, and a noise of a great rushing.
 So the spirit lifted me up, and took me away, and I went in bitterness, in the heat of my spirit; but the hand of the LORD was strong upon me.
In his letters Blake does not tell us of a particular event that marked a conversion experience but he tells us clearly through his poetry. Blake has a role for himself in in his book Milton in which he was able to give an account of the transformative experience of receiving the spirit which empowered him to write. Los, the prophetic entity of Blake's myth, plays the role of the Holy Spirit in descending to Blake and entering his Soul. This is a description of the empowering experience which removed for Blake any doubts about being called to speak as directed by God.
Milton, Plate 21 , (E 115) "But Milton entering my Foot; I saw in the nether Regions of the Imagination; also all men on Earth, And all in Heaven, saw in the nether regions of the Imagination In Ulro beneath Beulah, the vast breach of Miltons descent. But I knew not that it was Milton, for man cannot know What passes in his members till periods of Space & Time Reveal the secrets of Eternity: for more extensive Than any other earthly things, are Mans earthly lineaments. And all this Vegetable World appeard on my left Foot, As a bright sandal formd immortal of precious stones & gold: I stooped down & bound it on to walk forward thro' Eternity." Milton, Plate 22 , (E 116) "And Ololon lamented for Milton with a great lamentation. While Los heard indistinct in fear, what time I bound my sandals On; to walk forward thro' Eternity, Los descended to me: And Los behind me stood; a terrible flaming Sun: just close Behind my back; I turned round in terror, and behold. Los stood in that fierce glowing fire; & he also stoop'd down And bound my sandals on in Udan-Adan; trembling I stood Exceedingly with fear & terror, standing in the Vale Of Lambeth: but he kissed me and wishd me health. And I became One Man with him arising in my strength: Twas too late now to recede. Los had enterd into my soul: His terrors now posses'd me whole! I arose in fury & strength."
Library of Congress Milton Plate 47, Copy D