2:14. And now, my sons, I speak unto you these things for your profit and leading for there is a God, and he hath created all things, both the heavens and the earth, and all things that in them are, both things to act and things to be acted upon.
Things to act and things to be acted upon] The living and the dead, the animate and the inanimate- all are subject to the mind and will of God. Thus Nephi stated: "If God had commanded me to do all things I could do them. If he should command me that I should say unto this water, be thou earth, it should be earth; and if I should say it, it would be done." (1 Nephi 17:50.)
2:15. And to bring about his eternal purposes in the end of man, after he had created our first parents, and the beasts of the field and the fowls of the air, and in fine, all things which are created, it must needs be that there was an opposition; even the forbidden fruit in opposition to the tree of life; the one being sweet and the other bitter.
2:16. Wherefore, the Lord God gave unto man that he should act for himself. Wherefore, man could not act for himself save it should be that he was enticed by the one or the other.
Our first parents] Adam and Eve are the mortal parents of all. There is no scriptural justification for the idea of pre-Adamites. In a revelation directed to our day, Adam was declared to be the "father of all" (D&C 138:38). As to the manner in which Adam was placed on earth, the First Presidency of the Church (Joseph F. Smith, John R. Winder, and Anthon H. Lund), in an official statement titled "The Origin of Man," stated:
"[Adam] took upon him an appropriate body" the body of a man, and so became a 'living soul.' . . . All who have inhabited the earth since Adam have taken bodies and become souls in like manner. . . . Man began life as a human being, in the likeness of our Heavenly Father. True it is that the body of man enters upon its career as a tiny germ embryo, which becomes an infant, quickened at a certain stage by the spirit whose tabernacle it is, and the child, after being born, develops into a man. There is nothing in this, however, to indicate that the original man, the first of our race, began life as anything less than a man, or less than the human germ or embryo that becomes a man." (James R. Clark, comp., Messages of the First Presidency 4:200-206.)
Perhaps no story in scriptural writ matches that of Eden in its symbolic richness. In the midst of the Garden of Eden was the tree of life- a symbolic representation of Christ and immortality (see 1 Nephi 11:4-21). Standing opposite the tree of life was the tree of knowledge of good and evil. Each tree bore its distinctive fruit- the fruits of eternal life or of endless death, the one being sweet and the other bitter. Thus Adam and Eve could exercise agency, having a choice of which fruit they would partake. Had there been nothing within the garden that was forbidden to Adam and Eve- had there been no opposition- there could be neither agency nor progress available to them.