Answer:
I can be written, I can be spoken, I can be exposed, I can be broken.
I am a good state, there can be no doubt of itΝΎ But those who are in, entirely are out of it.
By Moon or by Sun, I shall be found. Yet I am undone, if there's no light around
As I walked along the path I saw something with four fingers and one thumb, but it was not flesh, fish, bone or fowl.
Put into a pit, locked beneath a grate, guarded through the night, yet it still goes out.
You use it between your head and your toes, the more it works the thinner it grows.
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?