From the earlier portions of this extract one may see how clearly Descartes distinguished between the idea, or the thing immediately known, and the external thing which he assumed as corresponding to the idea; from the latter part one may see how he sometimes confounded them. He finds that he may doubt whether ideas have any external correlatives; and, granting that they have, whether the two resemble each other at all. All this would imply that "external" things are completely cut off from observation. And yet he states with _naïveté_ that he has "often remarked in many instances that there is a great difference between an object and its idea." Now, if this can really be remarked in many instances, the doubt as to the existence of objects would seem to be groundless. How can it be remarked? On this point Descartes is silent. He has evidently fallen back upon the popular notion that under favorable circumstances one can get a look at a "real" thing, just as it is. The "reason" which convinces him that the astronomer's notion of the sun is the true notion is nothing but this. It could certainly not be deduced from his only argument for the existence of external things--the veracity of God. How does he know, that in giving us several different ideas of the sun, God has chosen to have this one only resemble it? It is a pure assumption. Reason is of service when one has something to go upon; but in the absence of premises it will not carry one far. This assumption is an illustration of what I had occasion to remark upon in criticizing Pyrrho; of the fact that, from the series of possible perceptions which we group together as one object, we are apt to select one, to us for some reason the most satisfactory one, and to regard it as more truly representing the object than the others. Descartes has followed this impulse, and made this perception the best representative of the "real" object. Had he always distinguished sameness in sense first from sameness in sense seventh, he would have seen how purely gratuitous is his assumption. The statement, too, that two different ideas of the sun cannot both resemble the same sun, shows how little he comprehended what it meant by the word same when used in the third sense. If by the sun we mean a whole series of possible perceptions, perhaps quite unlike each other, but all united and related in certain ways, there is nothing to prevent very dissimilar things from being like the same sun. Each of them need only resemble a single link in the series. By the words "the same sun" Descartes meant the same in sense first, but this sins against the proper meaning of the term. The difficulty is self-created. Descartes' sun reminds me of Berkeley's moon. This latter writer clearly perceived that there may be multiplicity and diversity where one attributes sameness in sense third. Note the following: