Chapter II · The Implements · Section 4: A modern tea-science reading — reading “杵臼一曰碓惟恒用者佳”

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Thesis

Read through modern tea science, “杵臼一曰碓惟恒用者佳” is not a lab result but a set of variables: cultivar, soil, light and plucking standard.

Text

“The pestle and mortar, also called dui, are best when they have long been in constant use.”

Context

杵臼（chǔ jiù）：捣茶用的杵和臼。碓（duì）：春米用的工具。恒用者：经常使用的。

Evidence

• Collation: "惟恒用者佳"各本一致。吴觉农注：常用的杵臼表面磨光、不伤茶膏，新者糙涩——古人对工具的"养"深有心得。
• Existing readings: 吴觉农指出：唐代饼茶需将蒸青叶捣烂成膏，杵臼即为此而设；"恒用者佳"说明器物经年使用后表面光滑顺手，暗合今日茶人"养器"之说。

Analysis

Modern tea science would split “杵臼一曰碓惟恒用者佳” into cultivar, soil, light and plucking variables. 吴觉农指出：唐代饼茶需将蒸青叶捣烂成膏，杵臼即为此而设；"恒用者佳"说明器物经年使用后表面光滑顺手，暗合今日茶人"养器"之说。 They remain testable, but only with their conditions attached.

Conclusion

The section does not give a universal rule. It demonstrates a method: read the text, the annotation and the Tang context together before making a modern claim.

Source: The Classic of Tea, Chapter II · The Implements, section 4; the original is in the public domain.

In Tang context, 吴觉农指出：唐代饼茶需将蒸青叶捣烂成膏，杵臼即为此而设；"恒用者佳"说明器物经年使用后表面光滑顺手，暗合今日茶人"养器"之说。. Tea was tribute, medicine and monastery drink at once, not a standalone commodity; the conclusion cannot be transferred without that context.

Storage adds another variable: moisture and temperature. "惟恒用者佳"各本一致。吴觉农注：常用的杵臼表面磨光、不伤茶膏，新者糙涩——古人对工具的"养"深有心得。 Old and young tea do not share one shelf life, so “the older the better” is not a rule.

As a new reader, I first took “杵臼一曰碓惟恒用者佳” as a conclusion. Reading the annotation to section 4 again, it is clearly a judgment with conditions attached.