As to the Fall itself we are told that the Lord planted “the tree of knowledge of good and evil” in the midst of the garden. (Moses 3:9.) To Adam and Eve the command came: “Of every tree of the garden thou mayest freely eat, But of the tree of knowledge of good and evil, thou shalt not eat of it, nevertheless, thou mayest choose for thyself, for it is given unto thee; but, remember that I forbid it, for in the day thou eatest thereof thou shalt surely die.” (Moses 3:16–17.) Again the account is speaking figuratively. What is meant by partaking of the fruit of the tree of the knowledge of good and evil is that our first parents complied with whatever laws were involved so that their bodies would change from their state of paradisiacal immortality to a state of natural mortality.
(Bruce R. McConkie, Ensign, June, 1982)
The Fairest Gem 