As Alexander Schmemann put it, God formed Adam hungry and gave him the world as his banquet. Every tree of the garden, including the tree of life, was on his menu, with only one restriction: Adam was not to eat the fruit from the tree of the knowledge of good and evil. I might add what some have suggested, that is, that the altar of Adam's worship in his obedience was the tree -- not eating as he was commanded by God being the truest form of worship, namely, faith. The tree was Adam's Sinai, Gerazim, and Jerusalem.
It is a sobering thought that the highest form of worship is self-denial (the refusal to give great credence to your own thoughts, words, and feelings and the trust which places higher than self the Word of the Lord. We do not live in a time of much self-denial. We have people clamoring for what they want to sing, want to say, and want to do. We have performers whose ministry is being in the limelight and showcasing either their musical gift or their spirituality (usually much greater than those who sit and listen). We have musicians who draw more attention to themselves as people than to the service of their song, supposedly for the Lord. We even have pastors who hog the spotlight as if their service in worship was to MC a variety show, keep it all moving with witty banter, and occasional proffer a tidbit of useful advice. It has been a long time in coming but it has taken over the whole evangelical wing of Christendom, dominates the non-denominational big box churches, and threatens to overtake the confessional churches as well.
But Schmemann had his key on it. The restriction was not there as a test to see what Adam would do but a gift and a place where Adam could demonstrate his trust in God and show forth his obedience in his refusal to bow to curiosity or self-interest. Of course, we all know how that turned out. Adam and all his many children have suffered from the unwillingness to bow before the Lord, to trust absolutely His Word, and to obey His voice perfectly as the righteousness of worship purely offered. So the call of Eden stood waiting until one would and could fulfill it. Another Adam, the Son of God in flesh and blood, came to stand in Adam's place and to trust the will of the Father even to death. He did so not as test or trial but as the One righteous through which the many would be made righteous.
We don't do much fasting anymore. One of my doctors fasts one day every week. He does so perhaps out of some religious desire but also out of the conviction that it is good for him. My will is not so strong. I often choose to fast for a meal or two (several times a week) but not so much for a full day. Of course this is not about a rule but about trust. It is not that food is bad (it is most certainly good and a gift from God). It is not that fasting earns points with God. There is no promise in this good work over the good works we know avail us nothing in terms of obtaining righteousness (but only show forth the righteousness of Christ already ours by baptism and faith).
Yet Jesus does not argue for the fast. He presumes it. When you fast... is what we heard on Ash Wednesday. Do not complain and contort yourself as if the outward piety were too great a burden but delight in the opportunity and give cheerful countenance to your fasting. Fasting is part of worship, of the self-denial born of positive trust in the Lord, in the sufficiency of His grace, in the confidence that His Word is bread for life, and in the demonstration of obedience that is and has always been part of faith.
Augustine reminds us that our hearts will not rest until they rest in the Lord. Perhaps it is not only our hearts but also our hunger. God created us with hunger for Him and sin confounded that hunger and taught us to try and satisfy it other places but it is satisfied only in the Lord and only by the self-denial that regards grace greater than desire. If we begin to learn this in Lent, we will have been made wise indeed!