In Judaism and Christianity, the tree of life (‘ēṣ haḥayyīm) is first described in of the Book of Genesis as being "in the midst of the Garden of Eden" with the tree of the knowledge of good and evil (עֵץ הַדַּעַת טוֹב וָרָע). After the fall of man, "lest he put forth his hand, and take also of the tree of life, and eat, and live for ever", cherubim and a flaming sword are placed at the east end of the Garden to guard the way to the tree of life. The tree of life has become the subject of some debate as to whether or not the tree of the knowledge of good and evil is the same tree.
In the Bible outside of Genesis, the term "tree of life" appears in Proverbs () and Revelation (). It also appears in 2 Esdras () and 4 Maccabees (), which are included among the Jewish apocrypha.
According to the Greek Apocalypse of Moses, the tree of life is also called the Tree of Mercy. Adam believed the oil of the tree of Life would relieve him of his ailments and sent Seth and Eve to the doors of the Garden to beg for some oil of the tree of Life.
Karl Budde, in his critical study of 1883, proposed that there was only one tree in the body of the Genesis narrative, and that it had been portrayed in two ways: one as the tree in the middle of the Garden, and two as the forbidden tree. Claus Westermann gave recognition to Budde's theory in 1976.
Ellen van Wolde noted that among Bible scholars "the trees are almost always dealt with separately and not related to each other" and that "attention is almost exclusively directed to the tree of knowledge of good and evil, whereas the tree of life is paid hardly any attention."
The Eastern Orthodox Church has traditionally understood the tree of life in Genesis as a prefiguration of the Cross, which humanity could not partake of until after the incarnation, death and resurrection of Jesus.
In The City of God (xiii.20–21), Augustine of Hippo offers great allowance for "spiritual" interpretations of the events in the garden, so long as such allegories do not rob the narrative of its historical reality.