翻译一句话,最好解释一下句型~~

翻译一句话,最好解释一下句型~~
For,whatever from its own confines passes changed,this is at once the death of that which before it was.
最后一个it指的是什么?

it指前边的whatever
for在这儿等于because
changed是个后置定语修饰confines
后边的that是个代词也指whatever
which引导的是定语丛句说明that
意思差不多就是：
因为当来自它边缘的任何东西经过的同时被变化,这就立刻变成那被变化之前的东西死亡的产物.
我想this的指代还得通过上下文