In Searching For Home, M. Craig Barnes writes:
When the Hebrews left slavery in Egypt and were making their way through the hard lessons of the wilderness...they were sustained by the daily gift of manna. This was a “fine flaky substance” that came as the blessing of bread from heaven. For the next forty years it served as the staple for the Hebrew diet. It had to be collected every morning, and everybody had to gather their own basketful.
Other than that, we don't know a thing about the bread from heaven. Neither did the Hebrews, who gave it the name manna because the word means, “What is it?” Every morning the mothers would gather some “What is it?” and place it on the table. Their children would ask, as they always do, “What is it?” and the moms would say, “Well, yes.”
It is striking that their daily nourishment through the purgatory of the wilderness was found in a question. This means that the manna was something of a sacrament that offered a ritualistic way of renewing the terms of their relationship with God.
As they took the manna into their bodies, they were also taking a question into their souls. “What is it, God, that you are doing? What are you asking me to leave behind, to do, to become?” Nothing is more nourishing for the soul than asking that question, because it takes the focus off of our dreams and resources, both of which have run dry, and it turns our faces toward the dreams of God that only he can deliver...
It is not our job to answer the question. That's God's responsibility, and he will fulfill it by the slow transformation of our lives. In time, we will see what God is doing, but by then we will feel less like worms crawling our way out of slavery and more like butterflies who are carried home on the gentle breeze of new mercies.
Later in the wilderness sojourn, some of the Hebrews got fed up with the uncertainty that had become their daily regimen of grace. So they started to complain saying, “If only we had meat to eat! We remember the fish we used to eat in Egypt for nothing, the cucumbers, the melons, the leeks, the onions, and the garlic: but now our strength is dried up, and there is nothing at all but this manna to look at.” As any nomad will tell you, a prayer that begins with the words “if only” is very dangerous because you may receive what you want, and then how will you explain your unhappiness?
We are told that it was the rabble among the Hebrews that got them complaining. This was a group that they brought with them from Egypt who were not true believers in God or in the transformation he would bring to their lives...The rabble's toleration for discomfort was low, and their capacity for complaint was high. That's both an unfortunate and infectious combination. It doesn't take much for the “strong craving” of the rabble to get everyone worked up into a lather of anxiety. That's when they all began to say, “If only we had meat to eat.”
The most dangerous rabble are not the complaining people around us, but the rabble that lives in every human heart...tempting us to be anxious, making us doubt God's love for us, and thus our devotion to him...
If asking “What is it?” is the means by which our faith in God's transforming work is nurtured, then complaining, “If only” may be seen as the anti-manna. When we ask questions of God for which we are not given immediate answers, we find room for faith to grow. Faith is what binds us to God when we don't see how all of this is leading us to the right place in life. Nothing is more deadly than turning our faces back to Egypt and saying “If only”...
Speaking these words preoccupies us with either the future or the past. It assures us that our happiness lies in those places that implicitly define our present life by what is missing. Thus, the words “if only” are always a judgment upon the present day...
Here's the great danger: when the present tense disappears in your life, so does the manna. The mysterious, life-giving, blessed grace of God only comes in the day you have. If you miss that daydreaming about the future or longing for the past, your soul will never find its only source of nurture and you'll never survive the journey. Without the ability to see what God is doing today you are always anxious, never at home, and thus never joyful.
The ninety-fifth Psalm depicts God's response to those who complained their way through the journey by constantly lamenting “if only” and living in a day other than the one they were given. The Lord said, “For forty years I loathed that generation and said, 'They are a people whose hearts go astray, and they do not regard my ways.'” Throughout the Bible we are given this same consistent message. Nothing grates on God quite as much as our complaining. He doesn't respond as strongly to our many other sins, even idolatry, as he does to our complaints. God just loathes complainers.
That's because they will never find their way home by complaining that the road is too hard. It's supposed to be hard. That's what turns us to God.