That this truly Critical position had not been attained when I. § 13 was written,[812] is shown not only by its concentration on the single problem of the validity of _a priori_ concepts, but also by its repeated assertion that representations can be consciously apprehended independently of all relation to the faculty of understanding. The directly counter assertion appears, however, in the sections (I. § 14, II.: first four paragraphs) which immediately follow in the text of the _Critique_--indicating that in the period represented by these latter the revolutionary discovery, the truly Copernican hypothesis, had at last been achieved. They constitute the second stage, and to it we may now proceed. =Second Stage.=--A 92-4 = B 124-7; A 95-7; A 110-14. =A 92-4=, I. § 14 (with the exception of the concluding classification of mental powers).--This section makes a fresh start; it stands in no necessary relation to any preceding section. The problem is still formulated, in its opening sentences, in terms reminiscent of the letter to Herz; but otherwise the standpoint is entirely new, and save for the wording of a single sentence (A 93: “if not intuited, yet”), is genuinely Critical. The phrase “possibility of experience” now appears, and is at once assigned the central rôle. The words “if not intuited, yet” in A 93 may possibly have been inserted later in order to tone down the flagrant contradiction with the preceding paragraphs. In any case, even this qualification is explicitly retracted in A 94. =A 95-7.=--The same standpoint appears in the first three paragraphs of Section II. The categories are “the _a priori_ conditions on which the possibility of experience depends.”[813] By the categories alone “can an object be thought.”[814] The further important point that only in their empirical employment do the categories have use and meaning is excellently developed. “An _a priori_ concept not referring to experience would be the logical form only of a concept, but not the concept itself by which something is thought.”[815] =A 110-14, II. 4.=--In this section also the argument starts afresh, indicating (if such evidence were required) that, like I. § 14, it must have been written independently of its present context. But the argument is now advanced one step further. The categories are recognised as simultaneously conditioning both unity of consciousness and objectivity. “There is but one experience ... as there is but one space and one time....” “The _a priori_ conditions of a possible experience are at the same time conditions of the possibility of objects of experience”[816] “...the necessity of these categories rests on the relation which our whole sensibility, and with it also all possible appearances, have to the original unity of apperception....”[817] Now also it is _emphasised_ that save in and through _a priori_ concepts no representations can exist for consciousness.