The bread which Israel had taken along out of Egypt sufficed for thirty-one days, and when they had consumed it, the whole congregation of the children of Israel murmured against their leader Moses. It was not only immediate want that oppressed them, but despair of a food supply for the future; for when they saw the vast, extensive, utterly barren wilderness before them, their courage gave way, and they said: "We migrated, expecting freedom, and now we are not even free from the cares of subsistence; we are not, as out leader promised, the happiest, but in truth the most unfortunate of men. After our leader's words had keyed us to the highest pitch of expectation, and had filled out ears with vain hopes, he tortures us with famine and does not provide even the necessary food. With the name of a new settlement he has deceived this great multitude; after he had succeeded in leading us from a well-known to an uninhabited land, he now plans to send us to the underworld, the last road of life.  'Would to God we had died by the hand of the Lord during the three days of darkness in the land of Egypt when we sat by the flesh-pots, and when we did eat bread to the full.'" In their exasperation they spoke untruths, for in reality they had suffered from want of food in Egypt, too, as the Egyptians had not given them enough to eat. 
In spite of the railings against him, Moses was not so much indignant about their words as about the fickleness of the people. After those many quite extraordinary experiences they had no right to expect merely the natural and the probable, but should cheerfully have trusted him; for, truly, in the sight of all, they had been shown the most tangible proofs of his reliability. When, on the other hand, Moses considered their distress, he forgave them; for he told himself that a multitude is by nature fickle, and allows itself to be easily influenced by impressions of the moment, which cast the past into oblivion, and engender despair of the future. 
God also forgave the unworthy conduct of Israel, and instead of being angry with them because they murmured against Him, when it should have been their duty to pray to Him, He was ready to grant them aid, saying to Moses, "They act according to their lights, and I will act according to Mine; not later than to-morrow morning manna will descend from heaven."
As a reward for Abraham's readiness, in answer to the summons to sacrifice Isaac, when he said, "Here am I," God promised manna to the descendants of Abraham with the same words, "Here I am." In the same way, during their wanderings through the wilderness, God repaid the descendants of Abraham for what their ancestor had done by the angels who visited him. He himself had fetched bread for them, and likewise God Himself caused bread to rain from heaven; he himself ran before them on their way, and likewise God moved before Israel; he had water fetched for them, and likewise God, through Moses, caused water to flow from the rock; he bade them seek shade under the tree, and likewise God had a cloud spread over Israel.  Then God spoke to Moses: "I will immediately reveal Myself without Jacob, 'I will rain bread from My treasure in heaven for you; and the people shall go out and gather a certain rate every day.'"
There were good reasons for not exceeding a day's ration in the daily downpour of manna. First, that they might be spared the need of carrying it on their wanderings; secondly, that they might daily receive it hot; and, lastly, that they might day by day depend upon God's aid, and in this way exercise themselves in faith. 
While the people were still abed, God fulfilled their desire, and rained down manna for them. For this food had been created on the second day of creation,  and ground by the angels, it later descended for the wanderers in the wilderness.  The mills are stationed in the third heaven, where manna is constantly being ground for the future use of the pious;  for in the future world manna will be set before them.  Manna deserves its name, "bread of the angels," not only because it is prepared by them, but because those who partake of it become equal to the angels in strength, and, furthermore, like them, have no need of easing themselves, as manna is entirely dissolved in the body. Not until they sinned, did they have to ease themselves like ordinary mortals. 
Manna also showed its heavenly origin in the miraculous flavor it possessed. There was no need of cooking or baking it, nor did it require any other preparation, and still it contained the flavor of every conceivable dish. One had only to desire a certain dish, and no sooner had he thought of it, than manna had the flavor of the dish desire. The same food had a different taste to every one who partook of it, according to his age; to the little children it tasted like milk, to the strong youths like bread, to the old men like honey, to the sick like barley steeped in oil and honey. 
As miraculous as the taste of manna was it descent from heaven. First came a north wind to sweep the floor of the desert; then a rain to wash it quite clean; then dew descended upon it, which was congealed into a solid substance by the wind, that it might serve as a table for the heaven-descending gold.  But, that no insects or vermin might settle on the manna, the frozen dew formed not only a tablecloth, but also a cover for the manna, so that it lay enclosed there as in a casket, protected from soiling or pollution above and below.