Blake was a poet, painter, and engraver who wrote, illustrated, and published his own texts, such as Songs of Innocence and Experience (1789), of which no more than twenty-three copies are known to exist. Blake never intended the book for mass production. Each copy was apparently executed at a different time, when a customer had commissioned it. No two copies are identical, there being many differences in the coloring. Blake undoubtedly knew the poetry of Issac Watts, and children representing a religious response to the world are common in his poems. Blake, however, departed utterly from the moralistic conventions of almost all eighteenth-century versifiers for children, and from the poetic fashions of his day. His books are not so much written for children (the Blakes had none of their own) as they are attempts to see the world through childlike visionary eyes. Although in this and in his later work he anticipated the Romantic Movement, he was virtually unknown to the children of his day. Blake's watercolor illustrations for Bunyan's The Pilgrim's Progress were not published in his lifetime, but were reproduced in a Limited Editions Club version in 1941. Bunyan's allegory means so many different things to so many different people that it has been exceedingly hard to illustrate. Although it has been illustrated hundreds of times, no definitive illustrations exist: "We await the day when a serious artist who knows and loves the text will succeed in illustrating it to more than a handful of admirers' satisfaction (Mahoney)."
