"What is it?" That's the name that the Israelites gave to the mysterious heavenly food which descended on them each night during their 40 year wilderness tour. They were given a couple of specific rules about the gathering of the manna. First, only take as much as you need (about two quarts per person) and second, don't save any for the next day. Of course, people tried to save it anyways and the leftovers turned bad and were filled with maggots. But why did God forbid the people from taking more than they needed? The only explanation given for this somewhat bizarre ritual was this; "Then you will know that I am the LORD your God.'" (Ex 16:12)
Every morning the Israelites got up needing God to provide for them. If manna didn't come, they didn't eat. So when the first batch came it was only natural for them to want to gather more than the daily allotment. By storing up more what were they saying about themselves? We have to provide for ourselves. More importantly what were they saying about God? We don't trust you. In his infinite wisdom and understanding of how we humans think...God set up a system which required his people to trust him. They had to trust God for their survival every day. They had to depend on God to show up every single day. If only we were so lucky.
The Israelites were placed in a situation where the only option was to trust him. Unfortunately, ironically, sadly it is in the moments of total helplessness that we usually learn to depend on him. Maybe we should seek to depend on God when things aren't desperate. Or perhaps we should see desperate times as an opportunity to learn to trust. The old saying goes, "Pray like it depends on God and work like it depends on you." That mentality sounds good but leads us to a view that portrays God like a fire extinguisher; something to call on in an emergency. God wants us to place him first. To see him as our source, our security, our provider, and the person we can always count on. Everything else is ultimately...just moldy bread.
Read the Bible in One Year Plan: Exodus 16-18