Professor Ansarian:
One of the interpretations the Holy Quran has about human is resembling him to tree. The Allah Almighty has resembled and likened human to two trees. One resemblance and interpretation that is used in Quran about human being is the pure tree and another tree is interpreted as the impure tree. The pure tree according to what Allah almighty said is a very fruitful tree which its products is not bound to time like other trees that produce fruit a month or two annually, but this tree has perpetual fruit. The impure tree doesn,t have a strong roots so that they can be permanent and its few fruits are also impure and is not usable by the people. The human being tree is planted pure and this tree is a manifestation of Allah Almighty,s power, knowledge and will. The human being is not impure in the first place, impurity is not the creation of Allah, and whatever comes from him is light and purity, if impurity and uncleanliness comes to human being it is because of their own actions and what they themselves did not the lord of the universe.
source : erfan.ir