yardstick
物差 — Measuring
The thing against which something else is measured.
Gold maravedí of Alfonso VIII1174–1217 (held to be struck at Toledo)
Écu d'orLate 16th to early 17th century
Twenty-franc gold coin of Ceres1851
Money itself is the measuring stick for society. If the measuring stick expands and contracts, everything it measures—prices, wages, debts—is thrown into disarray.