Surfaces can be rendered as radiant or ambient

There is an element of truth in every good lie. And in the most common errors.

Does the moon radiate light? Thinkers going back at least to Parmenides in the early fifth century BCE understood that the moon was not a generator of light but merely reflected the light of the sun.[i] Still, whenever we do something outside at night without artificial illumination, we say that we do it by moonlight. That is, we talk as-if and to some extent accept that the moon is the source of nighttime illumination. And, in a commonsense way, it is. What does this mean? 

Let’s return to JJ Gibson and the way he distinguishes radiant and ambient light. He says of radiant light that it “causes illumination … diverges from an energy source … has no structure … is propagated … [and] is energy.” Ambient light, by contrast, “is the result of illumination … converges to a point of observation … has structure … is not [propagated], it is simply there … [and] can be information.”[ii] The moon reflects radiant light from the sun which, especially at night, provides ambient light to observers. 

So much for the facts.

Every great story weaves numerous truths into a tapestry of lies that feels like a greater truth or, if not the same thing, expresses myths and meaning that tell us something that seems like it. The objective world is, therefore, a starting point: the intake and processing of information from it is central to defining humans as meaning-making animals. When we ask if the moon radiates, or shines, it is important to understand our role in the answer. Calvino notes that “the deepest rationality behind every literary operation has to be sought out in the anthropological needs to which it corresponds.”[iii]For the great fictions, myths, and meanings of night, we need a moon that casts its light upon the dark woods.

How does this illuminate (pun not intended but not edited out either) the work of architects? It is hard to get to the center of this point as it lies outside the realm theory wants to tread. Turning again to novelist Walker Percy and his suggestion that in order to see a place one must overcome the prescriptions for seeing it: “This dialectic of sightseeing cannot be taken into account by planners, for the object of the dialectic is nothing other than the subversion of the efforts of the planners.”[iv] That is to say, we cannot prescribe the anthropological needs that the inhabitants, users, experiences of our buildings will bring with them.

Then again, we know with some degree of precision the environmental vocabulary that humans bring to experiences of buildings and (maybe) works of architecture. Common agreement on identity is the beginning point of seeing that is more than mere sensation, as I’ve argued elsewhere. Perhaps we notice things more or better when those things’ identities begin to fray. That is not to say seeing is forgetting the name of the thing one sees but maybe that seeing is an active search spurred by perplexity at a name that doesn’t quite seem to fit. The distinction matters.

Marilynne Robinson’s observed that Shakespeare subverts or makes “power” strange. “So long as [power] retains its integrity it seems simply to define itself, to be self-evident. When it disintegrates it is revealed to be compounded of will, custom, kinship, loyalty, and opportunism, together with a magnetism of its own, which in some part always inheres even in fallen greatness.”[v] From this perspective, it is not surprising that eons of ancestors have marveled at the moon’s phases and been struck with awe at the magic of eclipses. And with only the smallest analogical jump, it is not hard to imagine that a building surface’s relation to light – here in shadow, here reflective, there seeming to glow – might call us to mystery or reverence. 


[i] Parmenides of Elea, Fragments: a text and translation with an introduction by David Gallop, (Toronto: University of Toronto Press, 1984), Fragments 14 and 15.

[ii] Gibson, The Ecological Approach to Visual Perception, 45.

[iii] Calvino, Six Memos for the Next Millennium, 27.

[iv] Percy, Message in the Bottle, 49-50.

[v] Robinson, The Givenness of Things, 45.

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