The wandering voices and the shadows these
  Of all that man becomes, the mediators
  Of that best worship, love, by him and us
  Given and returned; swift shapes and sounds, which grow
  More fair and soft as man grows wise and kind,
  And, veil by veil, evil and error fall.
  Such virtue has the cave and place around.
  [Turning to the SPIRIT OF THE HOUR.
  For thee, fair Spirit, one toil remains. Ione,
  Give her that curvèd shell, which Proteus old
  Made Asia's nuptial boon, breathing within it
  A voice to be accomplished, and which thou
  Didst hide in grass under the hollow rock.

IONE
  Thou most desired Hour, more loved and lovely
  Than all thy sisters, this is the mystic shell.
  See the pale azure fading into silver
  Lining it with a soft yet glowing light.
  Looks it not like lulled music sleeping there?

SPIRIT
  It seems in truth the fairest shell of Ocean:
  Its sound must be at once both sweet and strange.

PROMETHEUS
  Go, borne over the cities of mankind
  On whirlwind-footed coursers; once again