God created man in his image and established him in his friendship. A spiritual creature, man can live this friendship only in free submission to God. the prohibition against eating “of the tree of the knowledge of good and evil” spells this out: “for in the day that you eat of it, you shall die.” The “tree of the knowledge of good and evil” symbolically evokes the insurmountable limits that man, being a creature, must freely recognize and respect with trust. Man is dependent on his Creator, and subject to the laws of creation and to the moral norms that govern the use of freedom.
From the Catechism of the Catholic Church 396