Corrected entry: It is mentioned several times that only the Avatar can go to the spirit world, and speak with the spirits themselves. Yet, Commander Zhao, and several other humans, are able to not only find the Moon and Ocean spirits, but Zhao is even able to kill one of them.
wizard_of_gore
12th Jul 2010
Correction: There's a dfference between the spirit world and the spirit's forms in the real world. It is stated in the film that the water and moon spirits in the cave are spirits who have inhabited regular bodies on Earth. The spirit world is where the dragon spirit exists and where the spirits have real power.
Brad ★