When Jewish people conclude a satisfying meal that includes bread, they say four blessings.

Why?

Because the Torah says, “When you eat and you’re satisfied, you should bless G‑d for the land He has given you.”

The last three blessings were composed in the Promised Land. But the first blessing was composed by Moses when manna first appeared from heaven.

Now, isn’t it strange that we say a blessing that was composed for bread from heaven after eating bread that comes from the earth?

It gets yet stranger: The blessing is not on the food itself. It’s on our satiation from the food.

But manna was a food that never left you satisfied. For one thing, you could not see what you were eating. For another, you couldn’t save any of it for the next day.

Indeed, the rabbis call the manna, "bread of hunger," as Moses said, "He made you hungry, He made you starve, He fed you manna..."

So why do we say a blessing composed for a food that left people unsatisfied to thank G‑d for a satisfying meal?

It all makes sense once we grasp the psychology of gratitude. As the rabbis sum it up, “A full container cannot hold anything. But an empty one can hold everything.”

Human beings are very much like those containers—they need to learn to be empty in order to be full.

That is what occurred with those who ate manna for forty years:

Those who obsessed over keeping the bottle filled were always hungry. They had to hold tight to their possessions, because that was their security. And it was a very poor form of security, indeed.

But those who learned to be empty, to rely always on G‑d's blessing no matter how hard they worked—they gained satisfaction from every meal.

And when they settled the Land of Canaan, plowed it, seeded it, harvested it, and ate from its bounty, they continued to look to the heavens and thank G‑d for their meal.

The same with all of us: When we see our incomes as tangible assets, acquired and preserved by natural means, our possessions fill our lives so that we cannot see G‑d’s blessings.

But when we know that everything is always in G‑d’s hands, like manna from heaven, then we are empty and ready to receive.

Whatever you have, see it as a gift from Above, and celebrate.

Expect nothing and you will have everything.

Torat Menachem Sefer Hamaamarim Melukat, vol. 4, pg. 186.