Because I can find no useful or pleasant subject to discourse on, since the men who came before me have taken all the useful and pleasant subjects and discoursed on them at length, I find I must behave like a pauper who comes to the fair last, and can provide for himself in no other way than to take those things of trivial value that have been rejected by other buyers. I, then, will fill my shopping bag with all these despised and rejected wares, trash passed over by previous buyers, and take them and distribute them, not in the great cities, but in the poorest villages, taking whatever money might be offered.
I realize many will call my little work useless; these people, as far as I'm concerned, are like those whom Demetrius was talking about when he said that he cared no more for the wind that issued from their mouths than the wind the issued from their lower extremities. These men desire only material wealth and are utterly lacking in wisdom, which is the only true food and wealth for the mind. The soul is so much greater than the body, its possessions so much nobler than those of the body. So, whenever a person of this sort picks up any of my works to read, I half expect him to put it to his nose the way a monkey does, or ask me if its good to eat.
I also realize that I am not a literary man, and that certain people who know too much that is good for them will blame me, saying that I'm not a man of letters. Fools! Dolts! I may refute them the way Marius did to the Roman patricians when he said that some who adorn themselves with other people's labor won't allow me to do my own labor. These folks will say that since I have no skill at literature, I will not be able to decorously express what I'm talking about. What they don't know is that the subjects I am dealing with are to be dealt with by experience 1 rather than by words, and experience is the muse of all who write well. And so, as my muse, I will cite her in every case.
Although, unlike my critics, I am not able to facilely quote other writers, I will rely on an authority much greater and much more noble: on Experience, the Mistress of their Masters. These fellows waddle about puffed up and pretentious, all dressed up in the fruits, not of their own labors, but of other people's labors; these fellows will not allow me my own labors. They will scorn me as an inventor and a discoverer, but they should be blamed more, since they have invented and discovered nothing but rather go about holding forth and declaiming the ideas and works of others.
There are men who are discoverers and intermediaries and interpreters between Nature and Man, rather than boasters and declaimers of other people's work, and these must be admired and esteemed as the object in front of a mirror in comparison to the image seen in the mirror. The first is a real object in and of itself, the second is nothing. These people owe nothing to Nature; it is only good fortune that they wear a human form and if it weren't for this good fortune I'd classify them with the cattle and the animals.
There are many who would, with reason, blame me by pointing out that my proofs are contrary to established authority which is, after all, held in great reverence by their inexperienced minds. They do not realize that my works arise from unadulterated and simple experience, which is the one true mistress, the one true muse. The rules of experience are all that is needed to discern the true from the false; experience is what helps all men to look temperately for the possible, rather than cloaking oneself in ignorance, which can result in no good thing, so that, in the end, one abandons oneself to despair and melancholy.
Among all the studies of natural causes, Light more than anything else delights the beholder, and among the greatest features of Mathematics are the certainty of all its demonstrations which more than anything else elevates the mind of the thinker. Therefore, perspective is to be preferred to all other discourses and systems of knowledge, for in this science the ray of light is explained using methods of demonstration which glorify both Mathematics and Physics and grace the flowers of both these magnificent sciences. But since the axioms of Perspective have been treated extensively, I will abridge them, arranging them in their natural order and the order of their mathematical demonstration. Sometimes I will deduce the effects from their causes, and sometimes I will induce the causes from the effects, while adding my own conclusions that might be inferred from these.
On the three branches of perspective. There are three branches of perspective: first, the diminution of objects as they recede from the eye, known as Diminishing Perspective. Second, the way in which colors vary as they recede from the eye. Third, the explanation of how the objects in a picture ought to be less perfect and complete in proportion to their remoteness. The names are as follows: Linear Perspective, The Perspective of Color, The Perspective of Disappearance.
On the mistakes of those who practice without knowledge. Those who are fond of practice without knowledge are like a sailor in a ship without a rudder or a compass who, as a result, has no certain idea where he's going. Practice must always be built from sound theoretical knowledge. The gateway to this theoretical knowledge is Perspective; without Perspective nothing can be done well or properly in the matter of painting and drawing. The painter who only relies on practice and the eye, without any intellect, is no more than a mirror which copies slavishly everything placed in front of it and which has no consciousness of the existence of these things.
Here, right here, in the eye, here forms, here colors, right here the character of every part and every thing of the universe, are concentrated to a single point. How marvelous that point is! . . . In this small space, the universe can be completely reproduced and rearranged in its entire vastness! . . .
The ten attributes of the eye as concerns painting. Painting involves all ten attributes of sight: Darkness, Light, Solidity and Color, Form and Position, Distance and Nearness, Motion and Rest. This tiny treatise of mine will be only a brief study of these attributes of sight, for the purpose of reminding the painter of the rules and methods which should be used in his art in the project of imitating all the adornments and works of Nature. . . .
On the eye. If the eye is forced to look at an object far too close to it, that eye cannot really form a judgement of that object, for instance, when a man tries to look at his nose. As a general rule, then, Nature teaches us that no object can be seen perfectly unless it is placed at least at an distance from the eye equal to the length of the face.
The eye, which experience shows us sees all things upside-down, retains images. This is the proof: when the eye gazes at light for some time, it retains an impression, there remains in the eye images of brightness, that make less brilliant spots seem dark until the eye no longer has any trace of the image or impression of that brighter light.
Perspective is no more than a scientific demonstration in which experience shows us that every object sends its image to the eye by a pyramid of lines, and which shows that bodies of equal size will create a pyramid of larger or smaller size, according to their distance. A pyramid of lines are those which start from both the surface and the edges of the objects in question and which converge from a distance into a single point. A point is that which has no dimensions and is indivisible. This point is placed in the eye and receives all the points of the pyramid of lines.
The air is filled with an infinite number of images of all the objects in it. All these images are represented everywhere, all these images combine together: if you place two mirrors in such a way that they face each other perfectly, the first mirror will reflect into the second mirror and the second mirror will reflect into the first mirror. So: the first mirror takes the image of the second mirror and the second mirror takes the image of the first mirror, and each mirror takes the image of the other on to infinity, each mirror having within it a smaller mirror. This proves, by experience, that every object sends its image to every spot where that object can be seen. The reverse is also true: that very same object sending its image to every spot can also receive the images of all objects placed in front of it. Therefore, the human eye sends out its image through the air to all objects placed in front of it, including other eyes, and it also receives all the images of all the objects placed in front of it; it receives these images on its surface, communicates them to the common sense, which judges them, and if pleased with them, communicates them to the memory. As a result of this, I believe that the invisible images in the eye are also communicated to the object, as the image of the object is communicated to the eye. The images of objects are communicated throughout the atmosphere. Here's the proof: if you place several mirrors in a circle, they will reflect on each other to infinity. When one image reaches another, it will be returned to the object that produced it in the first place, and, now being a smaller image, it will return again to the object and then come back again, on and on to infinity. Here's another proof: if you put a light between two flat mirrors placed exactly apart, you will see in the mirrors an infinite number of lights, each smaller than the other. Here's another proof: if you put a light between the walls of a room, all parts of those walls will be illuminated in some way, if there is nothing to block the course of the image of the light. You can see this very same thing in the dissemination of the sun's rays, which in their entirety, and each by themselves, convey to the object the image of the object (the sun) which causes them. These experiments prove that each object fills the atmosphere with images of itself and receives the images of all other objects surrounding it. Therefore, every object is visible through the whole atmosphere, and the everything else is present in the smallest part, all the objects of the whole are visible each in all and all in every part. . . .
If the front of a building, or a piazza or a field, is lighted by the sun and has a house opposite it, and if you make a tiny hole in the side of the house not facing the sun, all the lighted objects of that building, or piazza, or field, will send images through that small hole and be visible in that house on the wall (which should be white) opposite the hole. These images will be upside-down. If you make any more small holes you'll get precisely the same results, so that the images of the lighted objects are completely present on the wall and on every part of it. Why does this happen? This hole must admit some light into the house, and the light admitted into the house will come from the lighted objects outside. If these objects have various colors and shapes, the light rays forming the images will have various colors and shapes; hence, the images on the wall.
Translated from the Italian by Richard Hooker