n8 The dissent criticizes our partial reliance on Gregory because the States' authority to "define and adjust the relations between debtors and creditors . . . [cannot] fairly be called essential to their independence." Post, at 18-19, n. 17 (internal quotations omitted). This ignores the fact that it is not state authority over debtor-creditor law in general that is at stake in this case, but the essential sovereign interest in the security and stability of title to land. See American Land Co. v. Zeiss, 219 U.S. 47, 60, 55 L. Ed. 82, 31 S. Ct. 200 (1911).