Answer:
Up on high I wave away but not a word can I say.
Blind but cruel.
Without this, H2O would just be 2O
There is one in every corner and two in every room.
I'm the source of all emotion, but I'm caged in a white prison.
Almost everyone needs it, asks for it, gives it. But almost nobody takes it.
Easy
Animal
Difficult
Food
Funny
Kids
Logic
What am I?