"A Slumber Did My Spirit Seal" by William Wordsworth is one of a group of five poems by Wordsworth known as the "Lucy poems", although in this poem, atypically, Lucy is not mentioned by name. Wordsworth composed these poems in 1798 and 1799 and published them in the 1800 edition of Lyrical Ballads. The identity of Lucy is unknown; she may have represented an individual, a composite, or have been purely imaginary.
What we do know about the character of Lucy from this and the other four poems is that she died at a relatively young (albeit not precisely specified) age. She appears to have been too young to have married, and is normally seen in natural or pastoral settings.
In "A Slumber did my Spirit Seal", Lucy is described in the first stanza as having a spiritual connection to nature. In the second stanza it is revealed that she is dead, unable to hear or see or move, and now in death completely part of the natural world in which she is buried.