perceived really measures, therefore, the greater or less imminence of a danger, the nearer or more remote fulfilment of a promise. And, consequently, our perception of an object distinct from our body, separated from our body by an interval, never expresses anything but a virtual action. But the more the distance decreases between this object and our body (the more, in other words, the danger becomes urgent or the promise immediate), the more does virtual action tend to pass into real action. Suppose the distance reduced to zero, that is to say that the object to be perceived coincides with our body, that is to say again, that our body is the object to be perceived. Then it is no longer virtual action, but real action, that this specialized perception will express: and this is exactly what affection is. Our sensations are, then, to our perceptions that which the real action of our body is to its possible or virtual action. Its virtual action concerns other objects, and is manifested within those objects; its real action concerns itself, and is manifested within its own substance. Everything then will happen as if, by a true return of real and virtual actions to their points of application or of origin, the external images were reflected by our body into surrounding space, and the real actions arrested by it within itself. And that is why its surface, the common limit of the external and the internal, is the only portion of space which is both perceived and felt.
