Allow me to raise points of debate on another forum as this is essentially identical to your other post.
Your question of purity based off of science is one that is flawed. I study chemistry and understand that the composition of an atom is actually shifting quite often with various levels to each atom's makeup. When one says "pure gold" it also includes isotopes which have more neutrons or electrons than the 'common weight' of the element. "Purity" even amidst a single compound is nonexistent unless extreme measures upon extreme measures are taken. This natural love of chaos could never be the creation of an essence of purity.
It is by the swirling chance of chaos and change that life began. It is by the vastness of extremes that species rose. It is by disparity that defined the champions of man and the villains. A search for purity is a search for natural 'stagnation' that allows no triumph or plight. An age of gray, constricted atmosphere that denies the very fabric or essence of life itself.