We have no idea how long Adam and Eve were in the garden. But we do know that at a certain point in time God kicked them out. During the time they were in the garden, certain rules applied: don’t eat of the tree of knowledge of good and evil, for instance. They could eat of the other trees, and we’ll assume that they ate of the tree of life. But after they had eaten of the tree of knowledge of good and evil, God set a new boundary to keep them from eating of the tree of life. A new era, or age, had begun: What was okay one day was not okay the next. Though the specifics vary, we can see this pattern repeated as one time period transitions into the next.