So the paper I write on, having the power in the light (I speak according to the common notion of light) to produce in men the sensation which I call white, it cannot but be the effect of such a power in something without the mind; since the mind has not the power to produce any such idea in itself: and being meant for nothing else but the effect of such a power that simple idea is words missing the sensation of white, in my mind, being the effect of that power which is in the paper to produce it, is perfectly adequate to that power; or else that power would produce a different idea.