God put the tree of knowledge of good and evil in the Garden of Eden to give Adam and Eve a choice to obey Him or disobey Him. Adam and Eve were free to do anything they wanted, except eat from the tree of knowledge of good and evil. They were given this choice of free will, and it was up to them if they wanted to obey or disobey God. This is referenced to compare the changes in nature to a loss of innocence in paradise. The sacred swamp is supposed to make us think of the Garden of Eden because when we think of swamps, we think yucky and bad, and the Garden of Eden is where they were banished from and was sent to Earth, since Eve had eaten a fruit from the tree. The author wants us to make this comparison because of when you do something bad, there is a negative consequence for it.
