Read it through once

PROSPERO. Dull thing, I say so; he, that Caliban, Whom now I keep in service. Thou best know’st What torment I did find thee in; thy groans Did make wolves howl, and penetrate the breasts Of ever-angry bears: it was a torment To lay upon the damn’d, which Sycorax Could not again undo; it was mine art, When I arriv’d and heard thee, that made gape The pine, and let thee out.