A hand with a short stroke added just below the wrist, pointing at the spot where the pulse is taken — one 寸 down from the palm. It is one of the clearest indicative characters in Chinese: a picture with a mark showing exactly which part is meant.
The 寸 is still the unit Chinese medicine uses to find pressure points on the body. 分寸 means a sense of proportion — 有分寸 is the compliment paid to someone who knows exactly how far to go. 一寸光阴一寸金: an inch of time is an inch of gold.
A hand with a mark at the wrist — one INCH down, right where the pulse beats.
一寸光阴一寸金 — an inch of time is worth an inch of gold — measures time with the same word used for the distance from palm to pulse.