Songs of Innocence and of Experience is a collection of 45 poems by English poet William Blake. "Songs of Innocence" is the first part of the collection and appeared in 1789 with engraved illustrations by Blake. The second part, "Songs of Experience," also illustrated, was added in 1794 when Blake published the whole under the full title of Songs of Innocence and Experience Showing the Two Contrary States of the Human Soul. The categories of innocence and experience are states of mind and ways of seeing that roughly correspond to the classical model of "paradise" and "fall," as in Milton's and Paradise Regained. Blake helped formulate the then contemporary Romantic notion of childhood as a state of innocence, without fear, inhibition, or corruption; and adulthood as a contrary and fallen state of original sin prey to oppression, corruption, and power. The opposition is reinforced by poems with like titles and contrasting themes in each part. The poems are short, simple, and acutely sensitive to both joys of life and the harsh realities of class and poverty in the emerging Industrial Revolution.