Where the thinker forgets the true function of the empirical concepts and is seized with the desire to develop them rationally, and thus to overcome the atomism of the scheme of classification and of extrinsic definition, he is led to refine them into abstract concepts, in which that scheme and that method of definition are overcome: the classification becomes a _series_ (numerical series, series of geometrical forms, etc.), and the definition becomes _genetic._ But this improvement not only makes the empirical concepts disappear, and is therefore not improvement but death (like the death which the empirical concepts find in true knowledge when they return or mount up again to pure thought); but such improvement substitutes for empiricism emptiness. Series and genetic definitions answer without doubt to demands of the practical spirit; but, as we know, they do not yield truth, not even the truth which lies at the bottom of an empirical concept or of a falsified and mutilated representation. Hence, here as elsewhere, empirical concepts and abstract concepts reveal their double one-sidedness, and exhibit more significantly the value of the unity which they break up; the distinction, which is not classification, but circle and unity; the definition, which is not an aggregate of intuitive data; the series, which is a complete series; the genesis, which is not abstract but ideal. VI OPPOSITION AND LOGICAL PRINCIPLES [Sidenote: _Opposite or contrary concepts._] By what has been said, we have made sufficiently clear the nature of distinct concepts, that is to say, unity in distinction and distinction in unity, and we have left no doubt as to the kind of unity which the concept affirms, that it is not _in spite of_ but _by means of_ distinction. But another difficulty seems to arise, due to another order of concepts, which are called _opposites_ or _contraries._ [Sidenote: _Their difference from distincts._]