Close your eyes and try to image how the world looks when no one is looking. You can’t, of course, because the “look” of something automatically involves you looking. This conundrum has bedeviled philosophy and science for centuries. Some people think we create our own reality. Others think our experience is dictated by atoms, molecules, and genes. But our experience does not depend on one factor only—the subjective self or objective reality—but on both together.

If the grass looks greener in springtime, there must be something about it different than brown grass at the end of summer—and different from the red skin of a ripe cherry. Yes, of course: chlorophyll! But why does chlorophyll produce in us the sensation of greenness rather than that of redness associated with the cherry? This sort of question involves the perceiver’s active role in perception. Perhaps greenness signifies something to the perceiver as an organism, in the way that pain signifies tissue damage and hunger signifies a need for nourishment. But, what?

This is a question that falls through the cracks between science and philosophy. Science has defined itself as a study of the natural world, not of subjective experience. Even psychology often embraces this “objective” approach, so that for decades it was far more about the experimental behavior of rats than the experience of people. Consciousness was an embarrassment, and still is for the physical sciences. Philosophy, on the other hand, is willing to ask silly questions, like: “Could I experience as red what you experience as green?” But the answer is no! You and I can expect to see grass roughly the same way because we are specimens of the same creature. Apart from chlorophyll, there is a reason in evolutionary history why grass looks green rather than red.

Think of experience as a kind of conversation the brain has with itself. Words have meanings, by social convention, which arise through common experience in the world to which they largely refer. Perhaps sensations get their “meanings” in a similar way, by convention that is not social but genetic, arising through experience in the world over thousands of generations. Nevertheless, we have the ability to play with words—and, to a limited extent, with perception. In both cases, we embrace a power to assign meaning and stretch the bonds of reality. Though I cannot will to see green as red, yet imagination, hallucination, painting and stained glass give me access to “greenness” as an experience dissociated from the usual objects.

What the world looks like “when no one is looking” can only mean what it happens to look like to our particular organism. This does not answer the question of why grass looks green rather than red, let alone why the world looks like anything at all. It does not solve the mystery of why consciousness exists, but it may be on the right track. One has conscious experience, in which the world figures prominently, because the human creature couldn’t have arisen and persist otherwise.

This brings to mind another silly question of philosophy: could a person behave exactly as they do, in every detail, but without conscious awareness? Again, certainly not! The fact that we are lit up inside with experience is functional; consciousness is essential to our survival. Not all of our behavior can be automatic or instinctual. If we are to respond to the world in all the sophisticated ways that human creatures do, there must be some particular way that it looks and sounds and smells and feels to us—the story we narrate to ourselves not only in words, but directly in the language of the senses.