Guy: Benjamin Franklin?
Guy: I bring a message from the future! I don't have much time.
Franklin: What is it?
Guy: The convention you're setting for electric charge is backward. The one left on glass by silk should be the negative charge.
(We were going to use the time machine to prevent the robot apocalypse, but the guy who built it was an electrical engineer.)note
"We travel through time to help history along - give it a push where it's needed. When the Omni's red, it means history's wrong. Our job is to get everything back on track."
"One more ship will make no difference in the here and now. But 22 years ago, one ship could have stopped this war before it started."
— Star Trek: The Next Generation, "Yesterday's Enterprise"