The Doctor raises an eyebrow at her last statement. It took some of the wind out of his sails. And with it, his voice softens slightly. Not with the compassion it had before, but he can accept that she at least takes responsibility, even if she may not understand things as he does.

"But you didn't manage to change anything. Which is for the best. Who knows what paradoxes you might have created."

One ordinary person is the most important thing in all of creation, after all. He had told Rose that when she had saved her father's life and Donna proved that too him time and again, just by being Donna.