by the objects, we should never be deceived in it, for it can never be denied that I truly perceive what I feel.
How, therefore, can I be deceived in the relation between these two Sticks, particularly, if they are not parallel? Why do I say, for instance, that the little one is a third part as long as the great one, when it is in reality only a fourth? Why is not the image, which is the sensation, conformable to its model, which is the object? It is because I am active when I judge, the operation which forms the comparison is defective, and my understanding, which judges of relations, mixes its errors with the truth of those sensations which are representative of objects.
Add to this the reflection, which I am certain you will think striking after duly weighing it, that if we were merely passive in the use of our senses, there would be no communication between them: so that it would be impossible for us to know that the body we touched with our hands and the object we saw with our eyes were one and the same. Either we should not be able to perceive external objects at all, or they would appear to exist as five perceptible substances of which we should have no method of ascertaining the identity.
Whatever name be given to that power of the mind which assembles and compares my sensations,—call it attention, meditation, reflection, or whatever you please,—certain it is that it exists in me, and not in the objects of those sensations. It is I alone who produce it, although it is displayed only in consequence of the impressions made on me by those objects. Without being so far master over myself as to perceive
