In Florence of the fifteenth century, Humanist artists made innovations in painting and drawing that eventually were adopted all over the world. The architect Filippo Brunelleschi invented the method of linear perspective that is still taught in elementary art classes. This requires the artist to establish the horizon line of the picture and to fix vanishing points on it. These indicate infinite distances; all parallel lines within the picture converge toward a single vanishing point. Leon Battista Alberti, another architect, wrote the first treatise on the method.
Leonardo of Vinci attempted to invent a method of shadow projection compatible with linear perspective. He was not entirely successful, but theorists of later centuries finished the task. The method requires an artist to fix not only vanishing points but also light sources; the manner in which shadows are cast by objects in the painting or drawing onto other objects in the painting or drawing is determined analytically.
The conventional wisdom says that the artists of the Italian Renaissance simply discovered the way to paint or draw realistically - that ancient and medieval men had always seen the world this way, but were not clever enough to figure out how to make pictures that matched what they saw.
Yet even a little consideration reveals that the system of linear perspective is unlike the reality that we perceive with our eyes and minds. We do not see with one unmoving eye, but with two eyes that move. When they focus on objects at a particular distance, objects at other distances split into transparent double images. Mentally, we place objects in our field of sight in relation to other objects, not in relation to an invisible grid. We do not see straight lines as straight, for one part of them is always closer to our eyes than the others. Our visions are received by retinæ that are concave, not flat; a flat painting or drawing distorts them in the same way that a map distorts the surface of a spherical planet. These distortions are exaggerated around the edges of the projection, especially if a large area is mapped. In a painting or drawing in linear perspective, these distortions can only be hidden by narrowing the field of sight.
What linear perspective accurately represents is what you will see when you hold still with one eye closed and look through a narrow frame at something distant. Brunelleschi intended to prove the truthfulness of the newly invented method; he set up a viewing-box by the portals of the unfinished cathedral building in Florence. Looking into the box through a small hole, a viewer could see the baptistery down the street, then a reflected painting in linear perspective of the same building. It worked (the painting looked just like the real baptistery), but only because the viewing-box created all of the specific conditions just described!
Neither does the similarity of paintings in linear perspective to photographs prove their truthfulness; cameras too are designed to create these specific conditions. And technology imparts its bias to its users. To a man with a hammer, everything looks like a nail; to a man with a camera, everything looks like a photograph. Have you ever seen somebody look at the real world that God made, then crane back his neck, close one eye and hold up his thumbs and forefingers at arms’ length to create a small rectangular frame for his field of vision? This is no way to comprehend, with all the saints, what is the breadth and length and height and depth....
Linear perspective is not a scientific discovery, but a suggestive form; it visually expresses the idea that reality exists within a grid of homogenous space. Alberti actually instructed artists to paint or draw while looking through a frame in which a perpendicular grid of strings has been fixed. The vanishing point suggests that infinity is an endless distance within created space. Such a definition would never have been accepted by apostolic, patristic or medieval Christians, for to them infinity was a divine attribute - something that cannot exist, even conceptually, within nature. The modern mind has become accustomed to thinking of eternity in the same way. To quote again Wolfgang Smith:
The popular idea of eternity is helplessly confused, for it reduces evidently to the concept of endless duration, which is an inherently contradictory notion, seeing that duration is defined by its terminations. Now eternity is endless, to be sure; but it is not a duration. Nor can we conceive of it as a limit by envisaging a sequence of durations approaching infinity. For it is not duration - however long - but the instantaneous moment that mirrors eternity.*******
What, then, is eternity? It is a state, or a plenitude of being, as both St. Augustine and Plotinus have observed, where has been and will be can find no place. There everything is concentrated within a single point, as it were: it is being that fully owns itself, without any scattering or dispersion. And yet it is not homogenous, but structured, if one may use that term; not empty, but perfectly full.
What, then, does a pious painting or drawing made with linear perspective and cast shadows represent? Not a view from eternity; the cast shadows fix everything in the picture at a single time of day. Not a view from Heaven; here the artist and the viewer imagine themselves as a mundane man who happens to be present at a holy event. If this man were to stand afar, hold still, close one eye and look through a narrow frame, the picture is like what he would see for a tiny length of time.
Now, I want to be very, very clear here; I am not saying that a painting or drawing like this is a bad thing, or a useless thing. I am not saying that it has no place in the Church. Its place is comparable perhaps to that of an imaginative prayer, rather than a liturgical prayer.
I am merely saying that painting or drawing like this is a different thing from a work of sacred art from apostolic, patristic or medieval times. And this different thing is not what the fathers of the Second Council of Nicæa had in mind when they declared:
The composition of religious imagery is not the painter’s invention, but is approved by the law and tradition of the Catholic Church. The tradition does not belong to the painter; the art alone is his. True arrangement and disposition belong to the holy fathers who established it.
Works quoted or referenced:
Erwin Panofsky, Perspective as Symbolic Form, translated by Christopher Wood, (New York: Zone Books, 1997).
Wolfgang Smith, Cosmos and Transcendence: Breaking Through the Barrier of Scientistic Belief, (San Raphael CA: Sophia Perennis, 2008).
Epiphanius of Constantinople, speaking at the Sixth Session of the Second Council of Nicæa.