Moses told Pharaoh, “Let my people go,” and after a lot of misery Pharaoh did just that. So the Children of Israel ate manna for 40 years. They ate quail, too, and sometimes–especially the priests–they ate the meat of sacrifices. But their diet (such is our impression) was mostly manna. Eventually they complained about this manna, this “insubstantial food” (Num. 21:5). How was it “insubstantial”? Rashi explains that it was completely absorbed, so there was no — um — waste.
Many children were born on the journey and presumably never learned a useful, perhaps essential, cultural skill.
When the Children of Israel got to their land, the manna stopped (Joshua 5:12), and they ate food from their new land.
After 40 years, they discovered new meaning in Moses’ old command.
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