Look not back. No, not even if you see the dearest and nearest cry. Look not back, but forward. We cannot stop. If we stop we die. We have either to go forward or to go backward. We have either to progress or to degenerate.
If my theory of relativity is proven successful, Germany will claim me as a German and France will declare me a citizen of the world. Should my theory prove untrue, France will say that I am a German, and Germany will declare that I am a Jew.