“Are colours real?” Eli asks.

We sit atop Fay Canyon in Sedona. Eli marvels at the dramatic changes he sees in the landscape around us. Late afternoon brings long rays of sunlight. Clay-brown cliffs turn to rich red and finally a golden glow.

“Well,” I say, “colour has a physical component and a perceptual component. Certain chemicals really are in the objects, and really reflect particular wavelengths of light. But how the light appears to us depends on our body’s visual receptors.”

Eli isn’t satisfied. The objects around us remain the same. So do our visual receptors. Only the angle of light changes. How is such dramatic variation possible?

“Are colours really real?” he persists.

“It depends on what you think is real,” I answer. “Some people think physical objects are most real; they would say that colour doesn’t change. Some people think that personal experience is most real; they certainly think that colours change.”

Later we walk on a narrow snowy trail. Trees close in on us, inviting us more deeply into our own thoughts.

“If something changes so much,” Eli asks, “Can it be real?”

“Something can change and still be real!” I snap. “You and I change all the time, and we’re real.”

“I mean, what do philosophers think?”

“Some philosophers think all real things change. Others think only what is eternal is real.”

“What’s an example of something eternal?” Eli asks.

“Numbers, a structure that underlies things. Or, if you’re religious, God.”

Eli ponders.

That evening, we go stargazing.

Astronomers bring telescopes and we look at “objects.” My favourite is the supergiant star Betelgeuse. To my eye, Betelgeuse looks red. That’s because, I am told, the star has burned up all its hydrogen.

Our astronomers affix a spectrometer to the telescope’s lens. Now Betelgeuse looks like a shimmering rainbow.

At irregular intervals, the rainbow is interrupted by thin black bands — a few particular frequencies of light that Betelgeuse can’t display. From this pattern of black bands, astronomers learn what chemicals are present in the star.

Or, more precisely: astronomers learn what was present in Betelgeuse 640 years ago. Because Betelgeuse is that far away, and the speed of light is that slow.

The epistemological categories of materialism and idealism are shaken.

Yes, colour has a physical and a perceptual component. But can you really separate the two?

With one perceptual apparatus, my unaided eye, Betelgeuse looks red. So, with the help of Chemistry 101, I learn about the star’s physical makeup: it is burning helium instead of hydrogen.

With another perceptual apparatus, a spectrometer-enhanced telescope, Betelgeuse looks like a shimmering spectrum. With the help of Astronomy 6101, I learn about the star’s physical patterns of pulsation, poles of rotation, and magnetic charge.

Astronomers may be convinced that perception leads them to a physical reality. Convinced, but not satisfied. They seek roads to new perceptual realities, so they can discover new physical realities. Restless minds can’t sit still in a single philosophical theory for long.

The metaphysical categories of permanence and change are also shaken.

Betelgeuse is our name for a mass of chemicals undergoing a long, slow thermonuclear reaction. The reaction is slow and stable enough to create an entity identifiable across millennia.

But to learn what Betelgeuse really is, astronomers study its changes over time.

We only know what is permanent by studying what changes. If we say permanence is more real, we deny the reliability of our information. If we say change is more real, we deny our powers of intellectual discernment. Permanence and change dance as a duo of intertwined, helpful ideas.

“Permanence” and “change” are temporal concepts. When you’re dealing in light years, what happens to the experience of time? From earth, we watch what happened on Betelgeuse 640 years ago. Does that mean, in some sense, what happened on Betelgeuse 640 years ago is also happening now?

Yes, sunsets and stars can set our minds spinning.

So can an iPhone camera.

The morning after Betelgeuse we walk along Oak Creek. With my iPhone, I take a picture of a lone mallard duck floating at the edge of shore.

My camera lens sees something else.

A bush that burns and is not consumed.

Instantly, I think of Moshe’s vision in the desert, as (Midrash says) he tries to chase down a lone lost sheep.

Is my camera a sort of spectrometer, an aid to perception, helping to reveal more clearly what really sits on shore?

Can empathy with an animal offer a momentary glimpse into what it sees, with its different perceptual apparatus?

Does the burning bush exist always and forever, waiting to be seen? Assuming it burned 3300 years ago, might it still be burning today? Could its type of thermonuclear reaction still be happening, and be discoverable only through altered or enhanced perception?

Yes, now I am leaving the kind of metaphysics endorsed by academic philosophy for a different kind of metaphysical speculation. The logical lines are no longer tight. But a restless mind throws out lines in many different directions.

Eventually some lines will be strong enough to hold.

Images: Oak Creek Canyon, Sedona, at the foot of Cathedral Rock, by Laura Duhan Kaplan using an iPhone 5.