
Probably in 1790 he finished The Marriage of Heaven and Hell of which there are nine known copies.
Many of Blake's best poems are found in two collections, Songs of Innocence from 1789, to which was added in 1794 the Songs of Experience, unlike the earlier work, never published on its own. Broadly speaking the collections look at human nature and society in optimistic and pessimistic terms, respectively—and Blake thinks that you need both sides to see the whole truth. The complete 1794 collection was titled:
Also see a collection of his paintings in a gallery.