What does とおす mean in the sentence 「声を落とせ。既に目は通してある。」？


I am not sure what the word 通す means in the context of
「声を落とせ。既に目は通してある。」(Lower your voice. I've already looked it over).

On Jisho, it says 通す means "to stick through" or "to (look, listen) through (a
window, wall, etc.)​," etc., but I do not know how these definitions apply
here. Is there something else, some other nuance, going on here? How does
既に目は通してある translate to "I've already looked it over."? I do not understand...




[目を通す is a common
idiom](https://jisho.org/word/%E7%9B%AE%E3%82%92%E9%80%9A%E3%81%99) you have
to remember, but this 通す is a transitive verb that means "to pass (something)"
or "to let (something) pass through". It's used like this:

  * パイプに水を通した。  
I passed water through the pipe.

  * このフィルムは水は通さないが空気は通す。  
This film doesn't let water pass but lets air pass.

So the literal meaning of 書類に目を通す is something like "to pass one's eyes
through the document" or "to make one's eyes go through the document". I think
you can now imagine why the idiom conveys the action of skimming a document to
get a general sense of its content.

