  With the basic ingredients of Berkeley’s ontology in place, we can begin to consider how his system works by seeing how he responds to a number of intuitively compelling objections to it. Berkeley himself sees very well how necessary this is: Much of the Principles is structured as a series of objections and replies, and in the Three Dialogues, once Philonous has rendered Hylas a reluctant convert to idealism, he devotes the rest of the book to convincing him that this is a philosophy which coheres well with common sense, at least better than materialism ever did.