Significance of The curse

The Witch of the Waste plans to combine Howl with Prince Justin and Wizard Suliman to make her perfect man. In order to capture Howl, she took a poem by John Donne and make it a curse to trap him. According to the curse, Howl will catch a falling star, see a child born of a mandrake root, find all past years and know who cleft the Devil's foot, hear mermaids sing, and then become honest. Once all of these things have happened, before Howl is ten thousand days old, the Witch will have him.