Part I, Chapter I

OF SENSE

Concerning human thoughts, I will consider them first singly, then in sequence or dependence upon one another. Taken singly, each is a representation or appearance of some quality or other attribute of a body outside us, commonly called an object. The object acts upon the eyes, ears, and other parts of the human body, and its different modes of action produce different appearances.

The origin of them all is what we call sense; for there is no conception in a human mind that was not first produced, wholly or in part, upon the organs of sense. All the rest derive from that origin.

To know the natural cause of sense is not strictly necessary to the present undertaking, and I have written about it at length elsewhere. Nevertheless, to give each part of my present method its due, I will briefly explain it here.

The cause of sense is the external body, or object, which presses upon the organ proper to each sense, either immediately, as in taste and touch, or indirectly, as in sight, hearing, and smell. This pressure, carried inward through the nerves and other fibers and membranes of the body to the brain and heart, causes there a resistance, or counterpressure: an effort by the heart to free itself. Because this effort is outward, it seems to be something outside us. And this seeming, or fancy, is what people call sense. To the eye it consists of light or color in a shape; to the ear, of sound; to the nostril, of odor; to the tongue and palate, of flavor; and to the rest of the body, of heat, cold, hardness, softness, and such other qualities as we discern by feeling. All these qualities called sensible are, in the object that causes them, only so many different motions of matter, pressing on our organs in different ways. Nor are they anything but different motions in us who are pressed, for motion produces nothing but motion. Yet their appearance to us is fancy, whether we are awake or dreaming. Just as pressing, rubbing, or striking the eye makes us fancy a light, and pressing the ear produces a din, so the bodies we see or hear produce the same effects by their powerful though imperceptible action. For if those colors and sounds were in the bodies or objects that cause them, they could not be separated from those bodies, as we see them separated through reflection in mirrors and echoes: the thing we see is in one place, the appearance in another. And although at a certain distance the real object itself seems clothed in the fancy it gives rise to in us, the object remains one thing, and its image or fancy another. Thus sense in every case is nothing but original fancy, caused, as I have said, by the pressure—that is, the motion—of external things upon our eyes, ears, and other organs appointed for that purpose.

But the schools of philosophy throughout the universities of Christendom, relying on certain texts of Aristotle, teach another doctrine. They say, to explain vision, that the thing seen sends out in every direction a visible species—that is, in English, a visible show, apparition, aspect, or “being seen”—and that its reception into the eye is seeing. To explain hearing, they say the thing heard sends out an audible species, an audible aspect or audible “being seen,” which enters the ear and makes hearing. Indeed, to explain understanding too, they say the thing understood sends out intelligible species, an intelligible “being seen,” which enters the understanding and makes us understand. I say this not because I disapprove of universities, but because I shall speak later of their office in a Commonwealth. I must therefore show you, as occasions arise, what needs reforming in them; among those things is their frequent use of meaningless speech.

CHAPTER II. OF IMAGINATION

OF SENSE

I will consider human thoughts first one at a time and then in a series, as they depend on one another. Each thought taken alone is a representation or appearance of some quality or other property of a body outside us, commonly called an object. The object acts on the eyes, ears, and other parts of a person's body. Its different actions produce different appearances.

The origin of all thoughts is what we call sense. No idea in a person's mind has not first arisen, in whole or in part, through the sense organs. Everything else comes from this origin.

Knowing the natural cause of sense is not very important to my present subject, and I have written about it at length elsewhere. Still, to make this part of my account complete, I will explain it briefly here.

The cause of sense is an external body, or object, that presses the organ appropriate to each sense. It presses directly in taste and touch, or indirectly in sight, hearing, and smell. This pressure passes inward through the nerves and other fibers and membranes of the body to the brain and heart. There it causes resistance, a counterpressure, an effort by the heart to free itself. Because that effort is directed outward, it seems to be something outside us. This seeming, or mental image, is what people call sense. For the eye it consists of light or color in a shape; for the ear, sound; for the nose, smell; for the tongue and palate, taste; and for the rest of the body, heat, cold, hardness, softness, and other qualities we detect by touch. All these qualities called sensible are, in the object that causes them, only different movements of matter, pressing on our organs in different ways. In us who are pressed, too, they are nothing other than different movements: movement produces only movement. But they appear to us as mental images, whether we are awake or dreaming. Pressing, rubbing, or striking an eye makes us imagine a light, and pressing an ear makes a noise. In the same way, the bodies we see and hear produce such effects by their strong action, even though we do not notice the action. If colors and sounds actually existed in the bodies or objects that cause them, they could not be separated from those objects. Yet we see them separated by reflection in mirrors and echoes: we know the thing seen is in one place and its appearance in another. At a certain distance the actual object may seem clothed in the image it produces in us. Even then, the object is one thing and the image or mental picture is another. Sense, then, is always simply the first mental image caused, as I said, by the pressure—that is, the movement—of external things against our eyes, ears, and other organs designed for sensing.

But the schools of philosophy throughout the universities of Christendom teach something else, based on certain passages in Aristotle. They say that, for sight to occur, the thing seen sends out in every direction a “visible species”—in English, a visible show, appearance, aspect, or “being seen.” The eye receives it, and that is seeing. To explain hearing, they say that the thing heard sends out an “audible species,” meaning an audible aspect or audible “being seen,” which enters the ear and makes hearing happen. Indeed, even to explain understanding, they say that the thing understood sends out “intelligible species,” meaning an intelligible “being seen,” which comes into the understanding and makes us understand. I do not say this because I disapprove of universities. But later I must discuss their role in a Common-wealth, so whenever the occasion arises I must show you what needs correcting in them. One such problem is their frequent use of words that mean nothing.

CHAPTER II. OF IMAGINATION