II. His Ruling Symbols from The Philosophy of Shelley’s Poetry in Ideas of Good and Evil by William Butler Yeats.

“His early romances and much throughout his poetry show how strong a fascination the traditions of magic and of the magical philosophy had cast over his mind, and one can hardly suppose that he had not brooded over their doctrine of symbols or signatures, though I do not find anything to show that he gave it any deep study.” [via]