In the narrative at the beginning of Genesis, we read that G‑d planted the Tree of Life and the Tree of Knowledge in the middle of the Garden of Eden (2:9). G‑d instructs Adam not to eat from the Tree of Knowledge (2:17). After Adam and Eve sin, G‑d banishes them from the Garden of Eden as a consequence of their sin—lest they eat from the Tree of Life and live forever (3:22).
Why hadn’t Adam eaten from the Tree of Life until then? After all, G‑d had forbidden him to eat only from the Tree of Knowledge?
I did a bit of research, and found in the commentaries several answers to your question. Here are a few of them:
- The fruit of the Tree of Life was effective only when ingested by a mortal who would otherwise die, like a medicine that holds potency only for one who is suffering from an illness. As death was only decreed upon the human being after—as a result of—the sin, Adam had no reason to eat of the fruit of the Tree of Life before that point.
- An interesting answer suggested by Nachmanides gives much food for thought. He suggests that the name eitz hada’at, usually translated as Tree of Knowledge, would actually be more accurately translated as Tree of Desire, and he cites several biblical instances where da’at is thus translated.
Prior to eating from the fruit of the tree, Nachmanides explains, Adam had no self-interests or desires—his sole objective was to serve his Creator. As such, he also had no motivation to eat from the Tree of Life, as G‑d had not instructed him to do so. Only upon Adam’s consumption from the Tree of Desire was G‑d concerned that he would have an urge to eat from the Tree of Life, and therefore took preventative measures to prevent that from occurring.
- Though he had no internal drive to deviate from G‑d’s command, there was an external evil influence, the serpent, that ensnared Adam and caused him to sin. The serpent, however, made no effort to entice Adam to eat of the Tree of Life, as his goal was to cause Adam to sin. And G‑d had not commanded Adam not to eat of the Tree of Life . . .
Please let me know if this helps.
Rabbi Baruch S. Davidson