I think the Tree of Knowledge is about having free will and choosing between what we need (God gives us what we need) and what we want (Satan/Devil/Evil gives us what we want).
This is how the evil in men triumphs over the good. Wants over needs.
It's the cycle of 'time', it's not linear as many suppose, it's circular, as in, The L-RD giveth and The L-RD taketh away, which brings us back to 'The L-RD giveth!
Go deep!
THE "BIBLICAL" VIEW OF TIME
The "normal" way most people look at time is linear. The past is "behind us," and the future "ahead of us." Adam and Eve existed about 6,000 years ago, the Torah came to Moses about 3,300 years ago, and the Messiah came about 2,000 years ago. This is all indeed true, from our point of view, from the "dimensions" we live in. As we will see however, there are a number of places in Scripture where things are hard to understand if we hold a linear view of time to be the only possibility.
The Biblical view of time is different. It is less concerned with "linear years" as it is with the cycle of events occuring within a year and the relationship these events have with God's eternal plan (i.e., references to them being a "picture" of what is in the heavenlies and a "shadow" of what is to come.)
http://www.yashanet.com/studies/revstudy/rev4a.htm
Yasha Net Studies
http://www.yashanet.com/studies/