The imagination always accompanies the idea, but is not itself the idea; and we perceive the evident and unimpeachable proof of the distinction between the two, if we ask ourselves, while in the very act of imagining a sea of light, an old man, an angry or placid countenance, a fountain or extension, if God is any one of these, or any thing resembling them; for, we very promptly answer, no, that this would be impossible. All this demonstrates the existence of an idea which has no connection with these representations, but essentially excludes what is contained in them. 24. What we have said of the idea of God, may be said of many other ideas. Rarely do we understand any thing into which the idea of relation does not enter as an indispensable element. How then is relation represented? In the imagination, in a thousand different manners; as the point of contact of two objects; as the link which unites them. But is relation any one of these? No! When we inquire in what it does consist, is there the slightest shadow of doubt that it is no one of these? Certainly not. 25. It is an error to call every idea an image, if you mean to consider ideas as something distinct from the intellectual act, which places itself before the understanding when it is in the exercise of its functions. An image is that which represents, as a likeness: and how, I ask, do we know that this representation or likeness exists? And how do we know that in order to reason we need an internal form, which is, as it were, a picture of the object? What is a picture beyond the sensible order? There are, it is true, similarities in the intellectual order, but not in the sense in which we perceive them in the material order. I think; so does my neighbor: here is a similarity, since the same thing is found in both one and the other, identical in species, but not in number. But this similarity is of a different order from that of sensible similarities. 26. When we understand, we know that which is in the object understood; but whether this be understood by a simple act of the intellect, or a medium be required to represent the similarity, we do not know. We understand the thing, not the idea; and it is as difficult to say how the intellect perceives without the idea, as it is to say how the supposed representation refers to its object. How does our idea refer to an object? If by itself, then by itself alone, since it is purely internal, it refers to the external, and requires no intermediary to place the subject in relation with external objects. What it does, the intellectual act of itself alone can also do. If we perceive the relation of the idea with the object by means of another idea, this intermediate idea presents the same difficulty as the preceding idea; and so at last we must come to a case in which there is a transition from the intellect to the object without any intermediary.