This morning I learned something. When I read “each silver plate weighing 130 shekels” in Numbers 7:85, it hit me that I had always thought a shekel was only a currency. Turns out it started as a unit of weight, and that sent me down a rabbit trail.
A shekel equaled about 11.4 grams of silver, or 0.025 pounds. A coin that weighed one shekel became worth one shekel. Value matched weight.
The shekel began in Mesopotamia around 2000 BC as a unit for trade. By the time it entered Israelite life around 1000 BC, it was standardized for religious use. “The shekel of the sanctuary” referred to the official temple weight, probably kept by priests to keep offerings fair. Later, during the Persian and Hellenistic periods, silver shekel coins were minted and circulated across the region. The shekel faded after the Roman era but came back in 1985 as the New Israeli Shekel (NIS), Israel’s current currency.
The British pound followed a similar path. It also began as a unit of weight. One pound of sterling silver equals 16 ounces, 7,000 grains, or 453.6 grams. That pound was divided into 240 pennies. So one ounce was valued at 20 pence. Why 20? There’s no clear law or decree. The Roman system divided a pound into 12 ounces, and over time each ounce came to be valued at 20 pence. It seems to have been a practical convention that stuck.
The old British system included shillings, crowns, and farthings. One pound was 20 shillings, one shilling was 12 pence. A crown was worth 5 shillings (60 pence). A farthing was one-fourth of a penny. It was layered, but people worked it out.
The official weight standard was literally stored in the Tower of London. All coins were compared against it to ensure they were honest. That was the physical “pound sterling.” In 1971, the UK switched to decimal: one pound = 100 new pence.
By contrast, today the metric system defines standards differently. The gram used to be defined by a platinum-iridium cylinder stored in France, but since 2019 it is tied to the Planck constant, a fixed value in physics, measured with a Kibble balance. No more chunks of metal in vaults. Now it is universal and grounded in nature itself. Honestly, I thought it was still physical until today.
So what about the pound today? In the US and UK, the pound is now officially defined by the metric system: exactly 0.45359237 kilograms. Ironically, the old imperial unit now depends on the very metric system it once resisted. No reference bar, no coin, just math.
Now you know what I know. Good morning.