Layers of reality
Reality can be described as having three different layers of reality: Physical Reality, Internal Reality and Social Reality. These realities can be hard to distinguish because they do not only overlap but are so intertwined with each other that every human being lives in all three of them at all times. Yet they are very different from each other, following very different kinds of laws of nature. And all of them are real. To understand the layers of reality may be central to understanding the nature of categorization.