Adam and Eve lived in a state of bliss and knew divinity personally. They chose to eat the "forbidden fruit" of the Tree of Knowledge. In Hebrew, the words are written tobve rah, which means "goodness and impurity." They imply the Tree of Knowledge is dual: it can be used for benefit through purity, or harm through pollution or impurity. Adam and Eve broke the commandment given to them by divinity, thus they became polluted by rah: impurity. That is how they lost the ability to walk and talk with Elohim.