What does そうなろう mean?


I was watching this anime events clip ->
<https://youtu.be/5y15wDpcwuI?t=6m12s>

and could not understand this particular part.

at 6:12 I think the seiyuu said

> **そうなろう** と思えば、 この世界はどこまでも残酷になれるのだということ

I could not find this word in the online dictionary, so maybe I heard
something wrong or is it possible that it simply mean "that".

* * *

At 6:23 I could not understand clearly what the other seiyuu said?

I believe it is

> 遠い昔に書かれたあるXXX
>
> XXX節がある




そうなろう is composed of:

  * そう: "so", "that"
  * なろう: the volitional form of なる ("to become")

そうなろうと思う literally means "(someone) thinks they want to become so".

And this そう refers to something said after it -- 残酷になる.

> そうなろうと思えば、この世界はどこまでも残酷になれる  
>  If this world wishes (to be cruel), this world can be infinitely cruel.

Yes this is an example of personification.

