Moses told Aaron to take a "tzintzeneth" and fill it with manna to preserve for future generations (Exodus 16:33). But what exactly was a tzintzeneth? The word appears nowhere else in the Hebrew Bible, leaving the rabbis to decode it from the word itself.
The Mekhilta runs through the possibilities. Was it silver? Iron? Lead? Copper? Tin? Any of these would make a practical container. But the rabbis noticed something embedded in the Hebrew letters. The word tzintzeneth contains the root "metztith," meaning something that can be seen through — something transparent.
The conclusion: it was an earthenware vessel, the kind from which glass is made. The manna jar was see-through. This was not an accident of vocabulary. The entire point of preserving the manna was so that future generations could look at it and know that God fed their ancestors with bread from heaven. A sealed metal box would defeat the purpose. The jar had to be transparent so people could actually see what was inside.
This small linguistic investigation reveals how carefully the rabbis read every unfamiliar word in the Torah. Nothing was decorative. If God chose the word tzintzeneth instead of a common term for "jar," there must be a reason. And the reason was visibility — the manna was meant to be witnessed, not just stored.