At the center of Shelley’s brash and uncompromising sense of the poet’s reach is his unabashed and unapologetic celebration of the visionary imagination. Alastor is no nature poem. It is rather nature as it ought to be, should be, could be but never will be. The narrator, who cautions that the Poet may push the imagination too far, may find its coaxing lure too fetching, recognizes in the sections before the Poet sets out to sea that the restless sense of the Poet may be heroic. The Poet cannot find contentment in the dance and play of the admittedly gorgeous but woefully limited elements of the world all around him. Whether it is the careless choreography of the natural world or the antique relics of humanity’s civilizations or the enticing divertissements of the social world (his loving family, his supportive friends, even his exotic lovers all pass through the poem), the Poet resists such accessible charms. They do not assuage his imagination.

In the poem’s elaborate allegory of the tumultuous sea journey and then the entrance into the wondrous cave, the poem introduces a stunning account of the imagination unbound. The colors dazzle, the shapes defy definition, the organic growth exceeds expectations, the place glows with an aura as unsettling as it is inviting; it is the real-time world exponentially magnified, idealized, through the visionary power of the perfervid poet.