touchstones

Touchstone is a standard or reference by which things are tested or judged; originally a piece of dark stone used to assay precious metals. Metals were rubbed on the touchstone and the color of the streak left on the surface indicated fineness, and the term has entered general language to mean a standard of comparison.

In philosophy and literature, a touchstone is a basic criterion or standard used to assess truth, quality, or authenticity. Critics may use a canonical work as a touchstone. The term is also used to describe a defining moment or experience that serves as a benchmark for character or judgment.

In everyday use, individuals refer to touchstones as guiding principles or core values that help evaluate actions and decisions. Organizations may declare touchstones—such as integrity, accountability, or innovation—as the core standards of behavior and performance.

In application, a touchstone can be an explicit criterion or an implicit reference point developed through experience. The phrase is often used metaphorically to indicate a reliable measure against which something is judged.