The Spectre is one aspect of the fourfold nature of the human psyche along with Humanity, Emanation and Shadow that William Blake used to explore his spiritual mythology throughout his poetry and art. As one of Blake's elements of the psyche, Spectre takes on symbolic meaning when referred to throughout his poems. According to professor Joseph Hogan, "Spectre functions to define individuals from others [...] When it is separated [from Emanation], it is reason, trying to define everything in terms of unchanging essences."[3] Thus, according to Samuel Foster Damon, Spectre epitomizes "Reason separated from humanity" and "Self-centered selfhood"[4] or, as Alexander S. Gourlay puts it, Spectre is "characterized by self-defensive rationalization".[5]
Spectre appears in several of Blake's works, including Jerusalem, Milton: a poem and The Four Zoas. Because of its widespread presence in Blake's more mythological works, scholars have reflected on Spectre through multiple critical approaches including Jungian archetypal analysis, as a means of mapping Blake's mythology within intellectual history and within his own biographical experience.