He begins with the curious case of color in dreams. When people today are asked whether they regularly dream in color, most say they do. But it was not always so. Back in the 1950s most said they dreamed in black and white. Presumably it can hardly be true that our grandparents had different brains that systematically left out the color we put in today. So this must be a matter of interpretation. Yet why such freedom about assigning color? Well, try this for an answer. Suppose that, not knowing quite what dreams are like, we tend to assume they must be like photographs or movies — pictures in the head. Then, when asked whether we dream in color we reach for the most readily available pictorial analogy. Understandably, 60 years ago this might have been black-and-white movies, while for most of us today it is the color version. But, here’s the thing: Neither analogy is necessarily the “right” one. Dreams don’t have to be pictures of any kind at all. They could be simply thoughts — and thoughts, even thoughts about color, are neither colored nor non-colored in themselves.