Mirror of Erised

 [inscription carved around the top]
"Erised stra ehru oyt ube cafru oyt on wohsi"
[But look closely it says backward that]
"I show not your face but your heart's desire"

It shows us nothing more or less than the deepest and most desperate desires of our hearts.

But remember this, this mirror gives us neither knowledge or truth.

Men have wasted away in front of it.

Even gone mad.

And I must ask you,

Not go looking for it again.

It does not do to dwell on dreams,

And forget to live

---words from movie