Image Biology

What do Shadows and Reflections have in common, and how do they differ?


When humour plays with shadows and reflections, it does so by twisting the relationship between the ‘casting object’, and its shadow or reflection. This creates a mismatch between the casting object; its ‘Original’, and the shadow or reflection; its ‘Image’.  Such a play is therefore comparable to the twists that play with the relationship between the Original and its Copy. Indeed, the easiest way to introduce the Original/Image relationship is to compare it to what we have already discovered about the Original/Copy relationship. And from that comparison, a list of Image Characteristics quickly emerges.

It turns out that images are like copies in some important ways, but they also differ from them in a number of significant respects:

1) Images are Ubiquitous      Copies are man-made, but images owe their existence to the nature of light as revealed on the surface of materials. So whereas copies emerge only here and there, and only where there is intelligent life, created to fulfil a meaningful purpose, images are ubiquitous, happening wherever the common conditions of light and surface are present, and therefore being totally without any kind of human purpose. Putting this another way, we might say that the sun is much less discriminating in its creation of images than man is in his creation of copies, so shadows and reflections vastly outnumber copies. Images are indeed everywhere.

2) Images are Insubstantial     Copies are fixed in the material world. This applies even to the two dimensional varieties, such as paintings and photos, though it is true they lack a little in depth. Images, on the other hand, are a function of light on certain surfaces, such as the earth, or a reflective surface such as water, and although these surfaces may often be grasped (such as with a mirror, or a screen for shadow play), the image itself remains physically elusive. In short, Copies have substance; but images have no substance at all. Images are insubstantial.

3) Images are Dependent     Copies, once created, are usually independent of their originals, but shadows and reflections can only ever exist by virtue of the physical immediacy of their original. Take away the casting object, and the shadow or reflection is gone. (This dependency is referred to as ‘Visual Correspondence’ from this point on). So it seems that, unlike the copy, an image must always share the context of its original, rather than having any special context of its own. (Additionally, not only is the image dependent on a casting object, but it is also dependent on the presence of a light source, and a suitable surface). So although copies are largely independent of their originals, images totally rely for their existence on the presence of their casting object. Images are dependent.

4) Images are both Faithful, and Inconstant    Whereas the Copy tends to be a finished product, the Image has an identity that is true to life, yet constantly changeable. A reflection in the water can be highly accurate, and yet if the wind ripples the surface, it changes. Similarly, a shadow may outline its object faithfully, but as the sun moves, so the shadow changes. Factors such as cloudy weather, multiple light sources, ripples in a pond, and corrugations on the ground can greatly compromise the fidelity of a shadow or reflection. Furthermore, the position of the original object relative to its light source and casting surface can greatly affect the integrity of the resulting image. So although images are totally faithful in perfect conditions, they can become highly erratic when those conditions decay. Images are both faithful and yet inconstant.

5) Images are great Followers     We have seen that Copies are made to follow their originals in looking like them, and even behaving like them. So if the original is suddenly changed for some reason, its copy does not immediately follow suit. For example, the sitter for a portrait may grow old (unless you are Dorian Gray), but the painting stays as it was. This is manifestly not the case in the Original/Image relationship. If the casting object of a shadow or reflection moves, its image moves too, and at a catch up speed of 300,000 kilometres per second.  In brief, unlike copies, images follow the object when it changes or moves, and do so at the speed of light. Images are therefore great followers.


Images are Ubiquitous, Insubstantial, Dependent, Faithful, but also Inconstant Followers of the world of Physical Objects


These general properties seem to apply to both shadows and reflections, as do the three factors of light source, object position and surface quality, all of which have their part to play in image creation. However, shadows and reflections do differ from each other, and in two important respects.

1) In terms of properties, a reflection can, and usually does give us the visual details of the surface of the original object. But the shadow only gives us a silhouette of its casting object, and that really is all we ever get. Or, to put this situation into the context of our own classification, the shadow has ‘property limitations’.

2) In terms of context, the shadow can be cast on many kinds of surface but the reflection needs a shiny surface. In practice, this means a reflection is limited to either a mirror of some kind, or a stretch of water. So unlike the shadow, the reflection is ‘context limited.

Talking about shadows and reflections as being limited in some way is clearly not the stuff of physics, where such phenomena are only understood in the pure terms of an objective science very far from our world of meaning. So for a physicist, these so called ‘limitations’ are merely the inevitable consequences of the properties of light on a world of surfaces. But does the cartoonist see his creative task in terms of this set of limitations? Well, they certainly have an effect on certain steps in the creative path yes. For example, if a mirror or lake has to be found for a reflection twist in a situation where the occurrence of either is difficult to contrive (the reflection is context limited), then this is a surely a problem? And if a lack of clear visual information in a shadow makes it harder to interpret what is happening in a twist (due to its property limitations), then again this could pose a problem, this time in our understanding of what the original casting object might be. So in principle, these limitations are likely to pose a real challenge for the cartoonist.

However in practice, the real answer to this question is that the cartoonist is not too bothered by these restrictions. This is because the search for a new image twist normally starts from within the context of the image that it is about to play with, so the light, object and surface conditions are already present for all to see. That is, the search for the twist does not start at an abstract level, but directly inside a situation already prepackaged with its mirror, pool or shadow-showing surface. So both the context and the properties are already set up at the starting point, and if either of the limitations are already in force, the starting point is moved to another example. Seemingly then, neither of these limitations restricts the creation of new image twists. Nevertheless, reflections and shadows do exhibit these limitations, and if nothing else, it can make a difference to the systematic creation of new examples, as we shall see further on in our investigation.