Its not impossible to seperate them - Yin and Yang have always been seperated one way or another since the beginning of time, mankinds ultimate test is to bring them back together, to do that the ultimate sacrifice is needed.
Can you say "there can be good without bad"?
Can you say "there can be light without shadows"?
Can you say "there can be enlightment without ignorance"?
...I can't, at least.
There can't be rich man without poor man lying in the world. If all people were meant to be rich, then they would not be rich... both rich and poor would dissappear, because they would be equal.