The missile knows where it is at all times. It knows this because it knows where it isn't. By subtracting where it is from where it isn't, or where it isn't from where it is (whichever is greater), it obtains a difference, or deviation. The guidance subsystem uses deviations to generate corrective commands to drive the missile from a position where it is to a position where it isn't, and arriving at a position where it wasn't, it now is. Consequently, the position where it is, is now the position that it wasn't, and it follows that the position that it was, is now the position that it isn't.

I sexually Identify as an Attack Helicopter. Ever since I was a boy I dreamed of soaring over the oilfields dropping hot sticky loads on disgusting foreigners. People say to me that a person being a helicopter is Impossible and I'm ♥♥♥♥♥♥♥ retarded but I don't care, I'm beautiful. I'm having a plastic surgeon install rotary blades, 30 mm cannons and AMG-114 Hellfire missiles on my body. From now on I want you guys to call me "Apache" and respect my right to kill from above and kill needlessly. If you can't accept me you're a heliphobe and need to check your vehicle privilege. Thank you for being so understanding.