Two versions, listen to both of them if you can, else the first one.
Nine Inch Nails - With Teeth
See the animal in it's cage that you built
Are you sure what side you're on
Better not look him too closely in the eye
Are you sure what side of the glass you are on
See the safety of the life you have built
Everything where it belongs
Feel the hollowness inside of your heart
And it's all
Right where it belongs
What if everything around you
Isn't quite as it seems
What if all the world you think you know
Is an elaborate dream
And if you look at your reflection
Is it all you wanted to be?
What if you could look right through the cracks
Would you find yourself
Find yourself afriad to see?
What if all the world's inside of your heart
Just creations of your own
Your devils and your gods
All the living and the dead
And you really are alone
You can live in this illusion
You can choose to believe
You keep looking but you can't find the words
Are you hiding in the dreams?