=Second Paragraph.=--This paragraph states (_a_) that through intuition we can represent only appearances, not things in themselves, and (_b_) that the appearances thus known exist only in us. Both assertions have implications, the discussion of which must be deferred to the _Analytic_. The mention of the “relations of things by themselves” may, as Vaihinger suggests,[565] be a survival from the time when (as in the _Dissertation_[566]) Kant sought to reduce spatial to dynamical relations. The assertion that things in themselves are completely unknown to us goes beyond what the _Aesthetic_ can establish and what Kant here requires to prove. His present thesis is only that no knowledge of things in themselves can be acquired either through the forms of space and time or through sensation; space and time are determined solely by our pure sensibility, and sensations by our empirical sensibility. Failure to recognise this is, in Kant’s view, one of the chief defects of the Leibnizian system. =Third and Fourth Paragraphs. Criticism of the Leibniz-Wolff Interpretation of Sensibility and of Appearance.=--Leibniz vitiates both conceptions. Sensibility does not differ from thought in clearness but in content. It is a difference of kind.[567] They originate in different sources, and neither can by any transformation be reduced to the other. “Even if an appearance could become completely transparent to us, such knowledge would remain _toto coelo_ different from knowledge of the object in itself.”[568] “Through observation and analysis of appearances we penetrate to the secrets of nature, and no one can say how far this may in time extend.... [But however far we advance, we shall never be able by means of] so ill-adapted an instrument of investigation [as our sensibility] to find anything except still other appearances, the non-sensuous cause of which we yet long to discover.”[569] We should still know only in terms of the two inalienable forms of our sensibility.[570] The dualism of thought and sense can never be transcended by the human mind. By no extension of its sphere or perfecting of its insight can sensuous knowledge be transformed into a conceptual apprehension of purely intelligible entities.