@@~Chaotic Discord~, Your posts in this thread make my brain so, so happy.
I completely agree with you. That tree is clearly very ancient. I do wonder if Discord is as old as the tree, or if Discord's personification (dragonification) of Chaos is something which has been handed down to him, in a way.
I always used to believe in my headcanon that Celestia and Discord were polar opposites. Celestia was the personification of Harmony and Discord the personification of Chaos. Celestia and Luna "rose up" to defeat him when he was already well-established, but (especially with the recent flashback proof) it is clear that Celestia and Luna were already alicorns and therefore already had strong magical prowess. They could (and I believe they are) as old as each other.
If Celestia didn't create the Elements and apparently didn't have a hoof in creating them either, but merely borrowed them, it is a possibility that Discord is a result of some other, more ancient power, that he in turn "borrowed" or had bestowed upon him in some way. I know that it's a little far-reaching and I don't have anything to base this on other than my own personal head-canon, but I still love thinking of Celestia and Discord as being completely equal opposites and this enables me to continue doing so.
Also, somepony else in this thread said that they thought Discord must know a lot about the Tree of Harmony. True, he planted Seeds of Doubt to try and destroy the tree, but I don't understand how he seemed oblivious to the Element's power before being turned to stone the first time.