One evening, Byron and Shelley discussed the ‘nature of the principle of life’ and how Dr Erasmus Darwin had experimented with giving movement to dead matter with electrical stimulation.
She dreamt of a student completing ‘the thing he had put together’ but then becoming terrified and hoping that 'left to itself’ would ‘subside into dead matter’.
The man went to sleep but ‘is awakened to behold ‘the horrid thing that stands at his bedside, opening his curtains, looking down on him with yellow, watery, but speculative eyes’.
Mary Shelley wished she could think of something as frightful for her own story, before realising that 'what terrifies me will terrify others' and began to write the tale upon this dream.