Letting go

Letting go was something that Rose Noble claimed a male-presenting Time Lord would never be able to understand. She and Donna, however, were able to rid themselves of the power of a Human-Time Lord Meta-Crisis by choosing to let it go. (TV: The Star Beast)

Behind the scenes
This dialogue of this scene, specifically that of claiming the Doctor could never understand the concept because he was "male-presenting" and "not a woman anymore", was criticised by many viewers for being unnecessary and sexist. It was especially seen as contradictory in contrast to the episode's overall message.