Fr. Barron gives us an answer, a most unpopular, yet brutally honest, answer:
The book of Genesis tells us that God placed his human creatures in the midst of a garden and gave them free rein to eat of practically all of the trees found there. Unlike the gods of classical mythology, the God of the Bible is not in a rivalrous relationship to human beings. On the contrary, his glory is that
we be fully alive, for he made us solely for the purpose of sharing his joy with us. This is why the Church Fathers consistently interpreted the trees in the Garden as evocative of philosophy, science, politics, art, stimulating conversation, friendship, sexuality—all the things that make human life rich and full. And it is furthermore why puritanical fussiness about pleasures both intellectual and sensual is simply not Biblical.
The original couple was told to refrain from eating the fruit of only one tree—and thereupon hangs a rather important tale. The tree in question is identified as the tree of “the knowledge of good and evil,” which is to say, a form of knowing that is the unique prerogative of God. Since God is himself the unconditioned good, he alone is the criterion of what is morally right and wrong. According to the semeiotics of this story, therefore, the eating of the fruit of the forbidden tree is the act of arrogating to oneself what belongs in a privileged way to God. It is to make of the human will itself the criterion of good and evil, and from this subtle move, on the Biblical reading, misery has followed as surely as night follows the day.
Notice how wickedly and cunningly the serpent tempted Eve: “God knows well that the moment you eat of it your eyes will be opened and you will be like gods who know what is good and what is evil.” The basic sin, the original sin, is precisely this self-deification, this apotheosizing of the will. Lest you think all of this is just abstract theological musing, remember the 1992 Supreme Court decision in the matter of Casey v. Planned Parenthood. Writing for the majority in that case, Justice Kennedy opined that “at the heart of liberty is the right to define one’s own concept of existence, of meaning, of the universe, of the mystery of human life.” Frankly, I can’t imagine a more perfect description of what it means to grasp at the tree of the knowledge of good and evil. If Justice Kennedy is right, individual freedom completely trumps objective value and becomes the indisputable criterion of right and wrong. And if the book of Genesis is right, such a move is the elemental dysfunction, the primordial mistake, the original calamity.
Of course, the Supreme Court simply gave formal expression to what is generally though unthematically accepted throughout much of contemporary western culture. How many people—especially young people—today would casually hold that the determination of ethical rectitude is largely if not exclusively the prerogative of the individual? That’s the fruit of eating of the tree of the knowledge of good and evil. Just after the fall, the first humans realized that they were naked and sought to cover themselves. I would interpret this, not so much as shame, but as deep and preoccupying self-consciousness. When we acknowledge that goodness and value lie outside of ourselves, in the objective order, we look outward, forgetting the self; but when we are convinced that our own freedom is the source of value, we tend to turn inward, protectively and fearfully.
What is fundamentally the problem, spiritually speaking? Why, deep down, are so many of us so unhappy? There is no better guide to answering these questions than chapter three of the book of Genesis.
No better guide, yet so widely ignored.
It's a frustrating thing to see so many rejecting the true wisdom of the ages.