But an incident occurred which is of some importance in the history of Shelley's psychological condition.

Toward midnight on the 18th of July, Byron recited the lines in "Christabel" about the lady's breast; when Shelley suddenly started up, shrieked, and fled from the room.

He had seen a vision of a woman with eyes instead of nipples.

At this time he was writing notes upon the phenomena of sleep to be inserted in his "Speculations on Metaphysics", and Mrs.Shelley informs us that the mere effort to remember dreams of thrilling or mysterious import so disturbed his nervous system that he had to relinquish the task.

At no period of his life was he wholly free from visions which had the reality of facts.
Sometimes they occurred in sleep, and were prolonged with painful vividness into his waking moments.