36. The subjection of these beings to necessary laws is not necessarily with respect to sensations, but is rather a mutual connection of their own. The connection of impressions which we receive from them is an effect of the dependence of some of them upon others; so that, in order to produce a determinate impression, we often employ an object which is, in itself considered, of no direct use, but which brings another into action, and so leads to what we desire. To raise a curtain has no connection with a magnificent landscape; and yet, oftentimes, we do nothing else when we wish to obtain a pleasant prospect. The relation in question is not then of sensations, but of their objects; the connection of these is what induces us to make use of one of them in order to obtain another. There is, therefore, outside of us a collection of beings subject to fixed laws, as well with respect to our sensations as to themselves mutually; therefore the external world exists, and the internal world, which represents it to us, is not a pure illusion. CHAPTER VII. ANALYSIS OF THE OBJECTIVENESS OF SENSATIONS. 37. Is the external world such as we believe it to be? Are the beings, called _bodies_, which cause our sensations in reality what we believe them? May we not, even after having demonstrated the existence of these beings, and their necessary subjection to constant laws, still doubt whether we have demonstrated the existence of bodies? Does it suffice for this to have proved the existence of external beings in relation among themselves and with us by means of laws fixed and independent of them as of ourselves? 38. Thoroughly to understand this question, it will be well to simplify it, and confine it to a single object. I hold in my hand and see an orange. I am certain, from what has just been demonstrated, that an external object exists in relation with other beings, and with myself, by necessary laws; I am also certain that I may receive different impressions from it; I see its color, size, and shape, perceive its odor, try its taste; feel in my hand its size, weight, and form, its concavities and convexities, and also hear a little noise when I press it with my hand. The idea of body is composite, and such is that of the orange; for it is that of something external, extended, colored, odorous, and savory. Whenever all these circumstances exist together, whenever I receive from an object these same impressions, I say that I see an orange. 39. Let us now examine how far the object corresponds to the sensations it causes in us.