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.
In the event that the position that it is in is not the position that it wasn't, the system has acquired a variation, the variation being the difference between where the missile is, and where it wasn't. If variation is considered to be a significant factor, it too may be corrected by the GEA. However, the missile must also know where it was.

Urgent footsteps race,
Toilet echoes distant plea,
Regret stains the floor.

⠄⠄⠄⠄⡀⡀⠄⠄⡀⠄⡀⠄⠄⠄⠄
⠄⠠⠂⠁⢂⠨⠡⡑⢀⠈⠄⠄⠄⠄⠄⠄⠄
⠑⠁⠂⠪⢈⢆⢧⡺⡜⡜⡌⡆⢆⠆⡆⣣⡣⡀
⡡⠨⠐⡐⡰⡑⡧⣫⡺⡱⡱⢘⠔⡑⢌⠎⣞⣵⠄
⠄⢂⠅⢬⡸⡮⣫⢧⠫⢊⠊⡂⠣⠊⢜⢪⢪⢺⣷
⠌⠄⢪⣺⢽⡹⣜⢔⠜⠔⠐⠄⢀⢈⠈⢔⢸⠱⠿⡀
⡮⢂⡳⡽⡵⡝⡎⡆⡊⠊⠄⢀⠄⠰⡽⡌⡇⠄⠄⣆
⢽⢈⢸⢹⡪⡯⡺⣪⠪⠌⡂⠄⢂⢽⣺⢪⢢⠂⢦⠌
⣽⢐⠘⢜⢎⠮⡫⢸⢘⠌⠄⠂⡢⡳⠭⢧⠣⡮⣪⡆
⠣⢂⡳⡑⠜⢈⠄⡳⠁⠄⡀⠡⢀⠐⢈⢘⡎⠅⡺⡇
⠈⡆⡅⠅⡃⠠⠄⢌⠂⠄⡈⠮⡢⢕⣐⣠⢳⠡⡻
⢊⢸⢱⠁⡂⢀⠄⠠⠁⠄⠈⠡⠒⠅⢕⣻⣦⢀⠅
⡤⡈⠂⢁⠐⠄⠄⠰⠄⠄⠈⠄⢈⠠⠠⢨⢆⢢⠁
⣞⣗⢧⡢⡀⡁⠄⢈⠂⠅⢀⠠⠄⠄⠄⡁⠂⣝
⣗⢗⢇⢯⢺⢨⢢⠄⠂⠅⠅⢀⠄⠂⠄⠔⢱⢹
⣞⡝⣎⢧⢳⡹⡼⡸⡐⠠⠐⢀⠈⠄⠁⢄⠣⠁

The robot clicked disapprovingly, gurgled briefly inside its cubical interior and extruded a pony glass of brownish liquid. "Sir, you will undoubtedly end up in a drunkard's grave, dead of hepatic cirrhosis," it informed me virtuously as it returned my ID card. I glared as I pushed the glass across the table.

He was an expert but not in a discipline that anyone could fully appreciate. He knew how to hold the cone just right so that the soft server ice-cream fell into it at the precise angle to form a perfect cone each and every time. It had taken years to perfect and he could now do it without even putting any thought behind it. Nobody seemed to fully understand the beauty of this accomplishment except for the new worker who watched in amazement.

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