"A slumber did my spirit seal" is a poem that was written by William Wordsworth in 1798 and first published in volume II of the 1800 edition of Lyrical Ballads. It is part of a series of poems written about a mysterious woman named Lucy, whom scholars have not been able to identify and are not sure whether she was real or fictional. Although the name Lucy is not directly mentioned in the poem, scholars nevertheless believe it to be part of the "Lucy poems" due to the poem's placement in Lyrical Ballads.