Our mirrors

Human eyes have a lot of stories to tell. They speak, they show, they smile, they cry - eyes reflect all of what you feel inside. Eyes can flirt, eyes can punish, eyes can transform your face into devilish one, erotic one, wondering one, sad one, happy one, tired one, sleepy one and so on, and so on... 

A person's thoughts can be ascertained by looking in his or her eyes. The face is a picture of the mind as the eyes are its interpreter. The face is the index of the mind. The eyes are the mirror of the soul. The eyes are the window of the soul.  

Here is something I have been wondering.

Why are the eyes called mirror of the soul ?

I'm sure everyone here have experienced looking in someones eyes and getting strange feelings...sometimes eyes are cold as ice and sometimes they are deep and dark etc.. list goes on.

But why is that so? And don't tell me it's biochemical reaction. 

The eyes tell the stories.... you can smile and be happy on the outside to the world but if someone looks into your eyes they'll see the real feelings.. Great when you can hide behind dark glasses.. You only show yourself to those you want to.
But as to the why it should be that way.. why they are mirrors I don't know. 

If you look someone into the eyes the first thing will be that you learn also about your own feelings. This is cruel, there are times when you need some privacy and there come some eyes and make you face the reality over and over again.