Coleridge often referred to his dreams as being like dramas, with their own characters, costumes, settings, and temporal and spatial conventions. The most essential quality likening dreams to drama was that both required the suspension of volition. From his earliest recorded thoughts on dreams, Coleridge considered the suspension of volition as one of the fundamental qualities of dreaming. Following from this, the illusory qualities inherent in watching a play are similar to the illusory qualities of a dream. He also often perceived his dreams as being performed on a stage – a space within which the actions and characters of the dream unfolded. He termed this theatrical dreaming space ‘Somnial or Morphean Space’ (CN iv 5360), and carefully recorded many of its features throughout his lifetime.

Both Andrew Baxter and Erasmus Darwin argued that in sleep the faculty of volition is suspended and therefore the many strange visions encountered in dreams are not considered surprising. Coleridge often remarked that when we are awake, the will is in control of all that is reasonable, creating the potential for the mind to be surprised by odd and unusual sights. The faculty for surprise exists in the waking state. In dreams, however, there is no sense of surprise, for all that happens is accepted without question (CN i 1250): the dreamer is bereft of a controlling sense of judgement, and no image or event is unlikely or surprising. This suspension of certain faculties requires the ‘voluntary Lending of the Will’ (CL iv 642). The question of the extent of the voluntary suspension of reason and volition is at the heart of Coleridge's analogy between the theories of drama and of dreaming.