William Blake (1757-1857) shared with other Romantic poets the belief that nature embodied truths more profound than the rational mind could apprehend, and that humanity's willful dissociation of itself from nature was the cause of most of the world's ills. But Blake embraced an exaltedly visionary view of the world and a mythic form of expression unique to himself. He also sought a means of rendering his works in a print form that might rival the dynamic, organic interplay of text, decoration, and illustration found in the best medieval illuminated manuscripts.
The technique Blake discovered is usually called "relief etching" to distinguish it from intaglio etching, in which the lines to be printed are lightly incised into a copper plate with an etching needle and are deepened and thickened when the plate is dipped in acid. Blake created his plates by first painting his texts and the lineaments of his illustrations and decorations on copper sheets with a very fine brush dipped in a clear acid-resist liquid. After painting the text and decoration, he immersed the plates in acid, which ate away their unpainted (that is, unprotected) areas. To print, he then inked the resulting relief portions of the plate (i.e., the lines of text, illustrative figures, and decorative lines), placed a sheet of paper upon the plate, and pressed it firmly, thereby transferring the ink from the plate's text and decorative elements onto the paper. In most of his books, all of the pages in each of the copies printed would then be water colored, usually in the identical color schemes, but embodying significant tonal differences.
Blake's two "prophetic" books arrived in the New York Public Library's Henry W. and Albert A. Berg Collection of English and American Literature in 1941, as part of the Owen D. Young Collection, one of the two most extensive collections of English and American literary manuscripts and printed books formed during the first half of the twentieth century. The other great collection belonged to W. T. H. Howe, which Albert Berg had bought some months earlier.