Ariel, in Shakespeare's The Tempest, is a magical spirit who, having been freed from the imprisonment imposed upon him by his earlier master, Sycorax, a mean-spirited witch, by Prospero is now condemned to find himself compelled to serve this new, albeit largely more benign, master. While Prospero has promised Ariel his freedom should the latter serve obediently and without complaint, the continued requirement to serve a master continues to bother the always helpful spirit. In Act I, Scene I, the ship transporting the former's nemeses, including Ferdinand, the reigning king's son, is caught in an enormous storm, or tempest, and the passengers are forced to abandon the vessel. These individuals, including Alonso, Prospero's brother who usurped the latter's rightful position as duke of Milan, are, per Prospero's instructions, allowed to live and are dispersed across the island now inhabited by the former duke of Milan and his daughter, Miranda. In Scene II, Prospero discusses with Ariel the ship's destruction and the survival of the passengers. Prospero had dispatched Ariel, who can change form at will and travel at great speed, to bring about the ship's ruin, although the inherently decent Prospero ensures that the ship's crew survives the storm. In any event, Prospero discusses the event with Ariel, in which the latter describes the ship's destruction through the spirit's efforts. It is in this context that Ariel, in describing how Prospero's nemeses jumped from the burning vessel into the sea, quotes Ferdinand's cry:
All but mariners
Plunged in the foaming brine and quit the vessel,
Then all afire with me: the king's son, Ferdinand,
With hair up-staring,--then like reeds, not hair,--
Was the first man that leap'd; cried, 'Hell is empty
And all the devils are here.'
So, what did Ferdinand mean by this exclamatory remark? As we learn, Alonso and the others conspired in Prospero's ouster and exile, and it is the former duke's intent to make his enemies pay for their treachery. Ferdinand, however, is not at all like his father. His observation that "hell is empty and all the devils are here" means that he recognizes the true character of his father and those with whom he has traveled, and that he views these men as essentially evil. Ariel's kind nature, however, influences Prospero in the latter's conduct of his vengeful plans. Oh, and Alonso is revealed as remorseful himself and merely prone to misguided acts of disloyalty.