An Island in the Moon is the name generally assigned to an untitled, unfinished prose satire by William Blake, written in late 1784. Containing early versions of three poems later included in Songs of Innocence (1789) and satirising the "contrived and empty productions of the contemporary culture", An Island demonstrates Blake's increasing dissatisfaction with convention and his developing interest in prophetic modes of expression. Referred to by William Butler Yeats and E. J. Ellis as "Blake's first true symbolic book," it also includes a partial description of Blake's soon-to-be-realised method of illuminated printing. The piece was unpublished during Blake's lifetime, and survives only in a single manuscript copy, residing in the Fitzwilliam Museum, in the University of Cambridge.