which refers to it, or that essence and existence are mutually independent. Any causal or other linkage between o and the idea will have to be later added as a third fact, involved neither in the mere essence of o nor in that of the idea, in case any such linkage is to be found.
Moreover, the essential independence of object and “mere idea,” in so far as each is first viewed by itself alone, will have to be a mutual independence. The idea will have to be, in its own separate essence, independent of the object. Otherwise, by merely examining the idea, taken by itself, you could prove something about the existence of its object. But, if so, then the that would follow from the what, and the independent existence of a thing from the presence of some mere idea of the thing. That, however, is forbidden by the whole spirit of realism. For that anything is, is a mere fact, to be wholly sundered from what anybody thinks it to be. So we can accordingly add that the object o also, when viewed in itself, might be supposed to change or to vanish without any change occurring in the idea of o. Of course if the idea is to remain true, it will indeed change when o changes, and so will be in that way dependent upon o. But then an idea might be false. That any given idea is true, or agrees with its object, is itself a further fact in a realistic world, a tertium quid. But this fact, like any other, may either be or not be. Mention to me a mere idea, define it as you will, and in a realistic world I have to say that this idea might be all that it now is whether or no any corresponding object exists in the real world.
