When Albany enters in Act 4, Scene 2, the exchange between wife and husband begins:
I have been worth the whistle.
You are not worth the dust which the rude wind
Blows in your face. I fear your disposition:
That nature, which contemns its origin,
Cannot be border'd certain in itself;
She that herself will sliver and disbranch
From her material sap, perforce must wither
And come to deadly use.
What is the “origin” that Goneril is said to “contemn” in the metaphor Albany employs here?