Originally written 巠, which depicts weaving vertical (warp) threads on a loom. The 糹 (thread) component was added later. Based on the original meaning "warp thread". The meaning later expanded to "pass through", "regulate", and "classic books".

Evolution

Bronze script

Late Western Zhou (~800 BC)

Seal script

Shuowen (~100 AD)

Clerical script

Eastern Han dynasty (25-220 AD)

Regular script

Modern

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