大般涅槃經義記 9.101

9.101

初中先喻，後合顯法。妄中無真名為「非內」，真不離妄說為「非外」，由非內故假修方得，由非外故修者必得。

In the first part, the analogy comes first, followed by the application to elucidate the doctrine. That there is no truth within delusion is called "not internal"; that truth is not separate from delusion is called "not external." Because it is not internal, it is attained only by relying on cultivation; because it is not external, those who cultivate will inevitably attain it.