The Tempest The Supernatural Quotes

How we cite our quotes: (Act.Scene.Line). Line numbers correspond to the 2008 Norton edition.

Quote #10

But this rough magic
I here abjure, and, when I have required
Some heavenly music, which even now I do,
                                     [Prospero gestures with his staff]
To work mine end upon their senses that
This airy charm is for, I'll break my staff, 
Bury it certain fathoms in the earth,
And deeper than did ever plummet sound
I'll drown my book. (5.1.59-66)

Here, Prospero promises to break his staff and give up his magic forever but immediately after delivering this speech, Prospero holds Alonso in a "charm" and later orders Ariel to make sure the seas are calm so the cast can enjoy a peaceful and safe passage back to Italy.  So, is Prospero actually ready to give up his "rough magic"?