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Rh is divided, inasmuch as these are the provinces where error has to be uprooted, and truth planted.

6. These three heads having been laid down as the general topics in reference to which error and contradiction prevail, the system then proceeds to search out these errors and contradictions, and to deal with them separately and in detail—the first aim of the inquiry, when it descends to these specialties, being to bring to light the leading or capital contradiction out of which all the others proceed.

7. The fundamental error of natural or ordinary thinking is found by the system to consist in an oversight of the primary law or condition of all knowledge. Natural thinking overlooks the necessity to which all intelligence is subject in the acquisition of knowledge—the necessity, namely, of apprehending itself along with whatever it apprehends. This oversight is equivalent to a denial, and, tested by the criterion of necessary truth, it amounts to a contradiction. It is tantamount to the assertion that a thing is not what it is—that "A is not A." Because, in asserting that knowledge can take place without its essential condition being complied with, it affirms that knowledge can be, without being knowledge (see Introduction,