I think that lions and mountains are real, and so are clouds and electrons. But the hypothesis that minds are brains does not support a kind of naive realism according to which things are just as we perceive or conceive them to be. We know enough about how brains work to show that both perceiving and theorizing are highly constructive processes involving complex inferences. Nevertheless, there are good reasons to believe that, when the brain is working well, it achieves knowledge about the reality of both everyday objects like mountains and theoretical scientific entities like electrons. This chapter shows how brain science and philosophical reflection together support a kind of constructive realism, the view that reality exists independently of minds, but that our knowledge of it is constructed by brain processes.