Every grey we mixed looked correct on the bench. Carried to the window, four of them turned green. Carried back under the tungsten, two of the survivors turned pink.
The bench lamp was 4000K, the window was overcast north light, and the tungsten was whatever had been in the fitting since before we moved in.
The lesson was not about pigment. It was that a decision made under one condition is a guess about every other condition, and we had been calling those guesses judgements.
Neutral is not a colour. It is a claim about the room.