Metaphysics is generally understood as the area of philosophy that deals with the problem of the meaning and structure of reality or existence. Many views have been advanced by philosophers, including Aristotle's objective realism, Plato's dualism, Descartes' conviction that consciousness appears at first as the absolute reality, Berkeley's conviction that "to be is to be perceived," and others. Briefly explain these various approaches to the problem of reality. What do you really think is truly real? Defend your answer.