Similarly, the Jews in the desert, even though their hunger was always assuaged, were afflicted because they had no way to ensure that there would be food tomorrow. The desert had only manna, plenty of it, but never enough to last until tomorrow. That man does not live by bread alone. The difference between desert and Land is not one of two different kinds of riches, provided by God from different sources, once the sky, once the land. God as the source of manna is not merely a substitute for a rich soil.
Wheat is dependent, apparently, on the attributes on the soil and the weather.
This picture of the desert is clearly depicted in the second section. You of course had water, and never met a scorpion, so that YOU lacked nothing, but the desert lacked everything. Manna is not known to your fathers - in other words, it is not food. Manna is not the food of Sinai - it is unknown, never known, neither to you nor to your fathers. Due to the obvious theological problems, the phrase has given rise to an extensive exegetical and philosophical literature.