You probably know that is just begining of his philosophy and it is not fair to stop here.Berkeley is not my favorite philosopher but we have to be fair when we analize his work.He was aware of problems wich his philosophy leed to and he made wayout."A tree will vanish if no one's looking at it."this means that existence of world depends of as,and he knew it is not good position.World exist even if it is no humans alive.So,how world exist?Because God is waching to the world.We can disagree with Berkeley but this is (in my opinion) fantastic wayout.