Although psychological evidence counts against the classical account of concepts as strictly definable, it does not suffice to enable us to choose definitively among prototype, exemplar, knowledge, and multimodal theories. But I see no reason to take these as competing views; rather I prefer to interpret them as capturing various aspects of how concepts are represented in the brain. Some concepts like mathematical ones may even be definable. In chapter 3 I suggested that concepts and other mental representations are patterns of neural activity. What I need to show now is that the brain-based view of concepts can support all these diverse aspects of concepts.