His work ranges from the deceptively simple and lyrical Songs of Innocence and their counterpoint Experience - which juxtapose poems such as 'The Lamb' and 'The Tyger', and 'The Blossom' and 'The Sick Rose' - to highly elaborate, apocalyptic works, such as The Four Zoas, Milton and Jerusalem. Throughout his life Blake drew on a rich heritage of philosophy, religion and myth, to create a poetic worlds illuminated by his spiritual and revolutionary beliefs that have fascinated, intrigued and enchanted readers for generations.

    The poem questions the way one can distinguish between reality and fantasy, asking, "Is all that we see or seem but a dream within a dream?"