
"Je ne parle pas français," http://digital.library.upenn.edu/women/mansfield/bliss/bliss.html#francais from Bliss and Other Stories (1920)
Variant: I have made it a rule of my life never to regret and never to look back. Regret is an appalling waste of energy, and no one who intends to become a writer can afford to indulge in it.
Context: I have made it a rule of my life never to regret and never to look back. Regret is an appalling waste of energy, and no one who intends to become a writer can afford to indulge in it. You can't get it into shape; you can't build on it; it's only good for wallowing in.