The Philosophy of Shelley's Poetry.
its properties, and beyond that experience how vain is argument, cannot create, it can only perceive;' and in another passage he defines mind as existence. Water is his great symbol of existence, and he continually meditates over its mysterious source. In his prose he tells how 'thought can with difficulty visit the intricate and winding chambers which it inhabits. It is like a river, whose rapid and perpetual stream flows outward.... The caverns of the mind are obscure and shadowy; or pervaded with a lustre, beautiful and bright indeed, but shining not beyond their portals.' When the Witch has passed in her boat from the caverned river, that is doubtless her own destiny, she passes along the Nile 'by Moeris and the Mareotid lakes,' and sees all human life shadowed upon its waters in shadows that 'never are erased but tremble ever'; and in many a dark and subterranean street under the Nile—new caverns—and along the bank of the Nile; and as she
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