It was a brand new world, pristine and holy. Adam was placed in this nurturing environment, and was given few instructions: To protect and work the Garden, to procreate…and then there was something about a tree.
And Almighty God planted a garden in Eden in the east, and He placed there the man whom He had formed. And Almighty God caused to sprout from the ground every tree that is pleasant to look at and good to eat, [including] the Tree of Life in the midst of the garden, and the Tree of Knowledge of good and evil. (Bereishit 2:8-9)
Now Almighty God took the man, and He placed him in the Garden of Eden to work it and to guard it. And Almighty God commanded man, saying, "Of every tree of the garden you may certainly eat. But of the Tree of Knowledge of good and evil you shall not eat, for on the day you eat from it, you shall surely die." (Bereishit 2:15-17)
With a beautiful, pastoral, idyllic life ahead, Adam and Eve do the unthinkable: They partake of the fruit of the deadly tree, the very tree they were warned about, and, indeed, the result is that death comes to the world.
In the aftermath of this monumental sin, God stations guards at the entrance to the Garden, to protect the Tree of Life (3:24). This tree has the power to counteract the poisonous effects of the Tree of Knowledge of Good and Evil. Had Adam and Eve been able to access the Tree of Life, the results of their transgression would have been neutralized. This leads us to raise an obvious question: Why did Adam and Eve not eat from the Tree of Life first, and only then eat from the Tree of Knowledge of Good and Evil? The fruit of the Tree of Life could have served as a prophylactic against the poison!
The Ohr Hachaim (3:22) addresses this question, and his answer is based on shrewd insight into the human psyche: Precisely because the Tree of Life was not prohibited, it was not alluring. Mankind has a peculiarly obsessive desire for the things that we cannot have, even – or perhaps especially - when these things might kill us. Adam and Eve had no trouble walking right past the Tree of Life, never giving it a second thought. It became attractive only after they had succumbed to the temptation of the forbidden fruit, only when they were in need of a cure for their self-inflicted suffering.
Other commentators are of the opinion that the Tree of Life was more of an antidote than an inoculation: It would have been ineffective against the effects of the Tree of Knowledge of Good and Evil had it been ingested before the sin. The “medicine” would work only after the patient became ill, not before.
If this is the case, a second question arises to replace the first: If the fruit of the Tree of Life is only effective as an antidote to sin, why did God create it, and then banish Adam and Eve from the Garden and deny their access to it, even going so far as to place armed guards to block the path lest they partake of this tree? (Bereishit 3:22-24)
Apparently, the answer lies in the timeline. Following the sin, God did not exile them immediately. Instead, He approached Adam slowly, gradually, and drew him into conversation. He left Adam time and opportunity to admit his guilt, to take responsibility for his actions. God engaged Adam, gave him cues to help him realize the enormity of the sin, and a window of opportunity to pray for forgiveness. Perhaps the Tree of Life was created in order to be used during this window of opportunity, in case man was unable to withstand temptation and fulfill the commandments he had been given. God created the poison, but he also created the antidote. All Adam had to do was express remorse and commit to improving his ways, and the antidote would have been available to him. Neither Adam nor Eve stepped up; they never expressed the slightest remorse nor asked God to forgive their sin, nor did either of them indicate in any way that they would try not to sin again. Perhaps they enjoyed the taste of the forbidden fruit so much that they were addicted to its poison.
In the final account, Adam and Eve, who were charged with protecting the Garden, instead became the ones to abuse it. Had they subsequently owned up to their offence, had they taken advantage of the time God offered to them to grapple with the meaning and repercussions of their actions, had they committed to more responsible and less self-destructive behavior in the future, the antidote stood right before their eyes, as it had been from the start. With the help of the Tree of Life, perhaps they might have been allowed to stay in the Garden to enjoy its fruits.
For a more in-depth analysis see: http://arikahn.blogspot.co.il/2015/10/essays-and-lectures-bereishit.html