Somebody built a machine to decide when they should rest.
They fed it sleep, soreness, appetite, and the previous week's tonnage,
and it was right eight times in ten, which is genuinely very good.

The trouble was never the two.
The trouble was that on the mornings it said go and the person felt wrong,
there was no lever for overruling it —
because overruling it had never been part of what they set out to build.

The Book of the Scholar — Wall 41:6