Targum Pseudo-Jonathan on Exodus 16:32 gives us one of the great commandments of Israel's memory: a jar of manna, set aside and preserved, so that later, less fortunate generations could see what the wilderness had tasted like.
Moses said: This is the thing which the Lord hath commanded to lay up of it a homer full to keep in your generations; that perverse generations may see the bread which you have eaten in the wilderness, in your coming forth out of the land of Mizraim.
"Perverse generations." The Aramaic daraya birshi'a is a blunt phrase. The Targum assumes that future Jews will sometimes lose their way, forget their origins, grumble as their ancestors grumbled, or worse. The jar of manna was preserved for those generations. Not for the pious. For the perverse.
According to the <a href='/categories/midrash-aggadah.html'>rabbinic tradition</a>, this jar was later placed in the Tabernacle alongside the Ark, and eventually in Solomon's Temple. The prophet Jeremiah (active c. 626-586 BCE) is said to have hidden it before the Babylonian destruction in 586 BCE, and it is one of the items that the <a href='/texts/bamidbar-rabbah-15-10.html'>Sages</a> teach will be revealed again in the days of the Messiah.
The Maggid pauses on the logic of the jar. A perverse generation will not be convinced by argument. It will not be shamed by rebuke. But a jar, a physical object, a few granules of bread that once fell from heaven, might still reach them. The Torah knows that sometimes the only language a lost generation understands is an object.
Takeaway: keep receipts. Whatever miracle you have lived through, preserve a piece of it, a photograph, an object, a letter, so that when you or your children later doubt, there is something in the jar to point to. Memory needs material. Faith has a physics.