monkey taming

After reading the book monkey taming, i realized what robbie williams song Me and my monkey is aboout, Different people have different monkeys, mine is the voice that scares me away from the food and having white teeth....robbies is the voice that drives him to drugs and drink.
I wonder how many different species of monkeys there are. Do most people with the same monkey feel its presants in the same way? Do they hear a voice or feel a feeling?
Are all mental problems describable as monkeys?

will be edited when I think of more to say!