Answer:
I don't have eyes, but once I did see. Once I had thoughts, but now I'm white and empty.
I'm not really more than holes tied to more holes. I'm strong as good steel, though not as stiff as a pole.
Round as a button, deep as a well. If you want me to talk, you must first pull my tail.
A leathery snake, with a stinging bite. I'll stay coiled up, unless I must fight.
A harvest sown and reaped on the same day in an unplowed field. Which increases without growing, remains whole though it is eaten within and without. Is useless and yet the staple of nations.
When is it bad luck to see a black cat?