Why can't the birdcage be cut?


Why does it appear that Doflamingo's Bird Cage is indestructible? What is the
different between the strings used in DD's attacks and the birdcage? Why can't
Zoro cut the birdcage?




[![enter image description
here!](https://i.stack.imgur.com/LmTCvm.jpg)](https://i.stack.imgur.com/LmTCv.jpg)

I don't think it is because Zoro cannot cut the cage that he is trying to push
it back. In chapter 270 he was in a similar situation, where he was trapped by
the _White Cage_ during the [Ordeal of
Iron](http://onepiece.wikia.com/wiki/Ordeal_of_Iron#Ordeal_of_Iron). At that
time he says it is completely unnecessary to trap him, because he is not going
to run away. Now, with the birdcage, the situation is similar in the sense
that he has no intention of running away. **Cutting the birdcage or running
away, will not benefit anyone with Doflamingo still around.** He will try to
kill anyone present at the island, with or without the birdcage.

Zoro knows this and knows that the person that will defeat Doflamingo is
Luffy, but he does not know how much more time Luffy will need. Therefore **to
buy Luffy as much time as he can and to prevent as much casualties as he can,
he tries to block the cage, instead of cutting it.** We have no clue what
would happen if he cuts the cage and it will probably require much needed
energy, which will probably just go to waste by cutting the cage over and over
again, because we all know Doflamingo will keep putting it up again and again.

Now as to your question whether the birdcage is indestructible, **that has not
yet been revealed up until the latest chapter 787**. Other than a few unknown
pirates and the meteor from Fujitora, there has not been a single person that
has actually tried to attack the cage, not now, nor in the flash-back.
Therefore it is hard to say how strong the strings actually are.

