Ok, so in the scene in the Last episode of Avatar the Last Airbender Aang has Aizen in a hold and starts the process of bending his energy within right.

And then we hear the voice of The Lion Turtle saying "that in order to bend one's energy that you spirit must be unbendable" or else it will basically result in something really bad on your part.

Now I was a little lost at that comment because it got me thinking about how did Aang make his spirit unbendable?

Was it by having Aizen's hands bound by the rock slabs, I don't know, but if anyone might know or have any speculations then I would really like to know, it's kinda bugging me hehe.

I put to much thought into it ^_^.

P.S. - no smarta** remarks please, let's be adults about this, Thank You.