Answer:
I am always hungry, I must always be fed. The finger I lick will soon turn red.
Though desert men once called me God, today men call me mad. For I wag my tail when I am angry. And growl when I am glad.
I am so simple that I can only point. Yet I guide men all over the world.
What can be measured but not seen?
I turn around once. What is out will not get in. I turn around again. What is in will not get out.
What is always coming but never arrives?