In the third place, “however, these monads must at the same time have certain qualities or determinations in themselves, inner actions, through which they are distinguished from others. There cannot be two things alike, for otherwise they would not be two, they would not be different, but one and the same.”[250] Here then Leibnitz’s axiom of the undistinguishable comes into words. What is not in itself distinguished is not distinguished. This may be taken in a trivial sense, as that there are not two individuals which are alike. To such sensuous things the maxim has no application, it is _prima facie_ indifferent whether there are things which are alike or not; there may also be always a difference of space. This is the superficial sense, which does not concern us. The more intimate sense is, however, that each thing is in itself something determined, distinguishing itself from others implicitly or in itself. Whether two things are like or unlike is only a comparison which we make, which falls within our ken. But what we have further to consider is the determined difference in themselves. The difference must be a difference in themselves, not for our comparison, for the subject must have the difference as its own peculiar characteristic or determination, _i.e._ the determination must be immanent in the individual. Not only do we distinguish the animal by its claws, but it distinguishes itself essentially thereby, it defends itself, it preserves itself. If two things are different only in being two, then each of them is one; but the fact of their being two does not constitute a distinction between them; the determined difference in itself is the principal point.