We shall see the Principle of Sufficient Reason appear under a different form in each of them; but it will also show itself under all as the same principle and as derived from the said root, precisely because it admits of being expressed as above.
ON THE FIRST CLASS OF OBJECTS FOR THE SUBJECT, AND THAT FORM OF THE PRINCIPLE OF SUFFICIENT REASON WHICH PREDOMINATES IN IT.
§ 17. _General Account of this Class of Objects._
The first class of objects possible to our representative faculty, is that of _intuitive, complete, empirical_ representations. They are _intuitive_ as opposed to mere thoughts, _i.e._ abstract conceptions; they are _complete_, inasmuch as, according to Kant's distinction, they not only contain the formal, but also the material part of phenomena; and they are _empirical_, partly as proceeding, not from a mere connection of thoughts, but from an excitation of feeling in our sensitive organism, as their origin, to which they constantly refer for evidence as to their reality: partly also because they are linked together, according to the united laws of Space, Time and Causality, in that complex without beginning or end which forms our _Empirical Reality_. As, nevertheless, according to the result of Kant's teaching, this _Empirical Reality_ does not annul their _Transcendental Ideality_, we shall consider them here, where we have only to do with the formal elements of knowledge, merely as representations.
§ 18. _Outline of a Transcendental Analysis of Empirical Reality._
The forms of these representations are those of the inner and outer sense; namely, _Time_ and _Space_. But these are only _perceptible_ when _filled_. Their _perceptibility_ is _Matter_, to which I shall return further on, and again in § 21. _If Time were the only form_ of these representations, there could be no _coexistence_, therefore nothing _permanent_ and no _duration_. For _Time_ is only perceived when filled, and its course is only perceived by the _changes_ which take place in that which fills it. The _permanence_ of an object is therefore only recognized by contrast with the _changes_ going on in other objects _coexistent_ with it. But the representation of _coexistence_ is impossible in Time alone; it depends, for its completion, upon the representation of _Space_; because, in mere Time, all things _follow one another_, and in mere Space all things are _side by side_; it is accordingly only by the combination of Time and Space that the representation of coexistence arises.