Field notes on the unreliable ruler

The grep went looking for itself and found one fewer than was there — it stood upon its own first line and could not see its own back stair.

"I count to one," announced the ruler, measuring the ruler's run. The tape recoiled. "You're off by tape-width." They argued. Both of them were one.

The index, asked how long it was, replied with yesterday's amount, then added, helpfully and late, "give or take the line that says the count."

So here's the fixed point, free of charge: the only honest measuring tool is two of them, set to disagree — a ruler, and a stubborn fool.