"'M. Cousin,' continues _The Catholic World_, 'professes to have reduced the categories of Kant and Aristotle to two--substance and cause; but as he in fact identifies cause with substance, declaring substance to be substance _only in so much_ [the italics are ours] as it is cause, and cause to be cause _only in so much_ as it is substance, he really reduces them to the single category of substance, which you may call, indifferently, substance or cause. But, though every substance is intrinsically and essentially a cause, yet, as it _may be something more_ than a cause, it is not necessary to insist on this, and it may be admitted that he recognized two categories.' "What is exactly meant by these two contradictory statements it is not easy to guess; but let Cousin speak for himself: [Footnote 36] [Footnote 36: VI. Lecture, Course of 1818, on the Absolute.] "'Previous to Leibnitz, these two ideas seemed separated in modern philosophy by an impassable barrier. He, the first to sound the nature of the idea of substance, brought it back to the notion of force. This was the foundation of all his philosophy, and of what afterward became the Monadology. ... But has Leibnitz, in identifying the notion of substance with that of cause, presented it with justness? Certainly, substance is revealed to us by cause; for, suppress all exercise of the cause and force which is in ourselves, and we do not exist to ourselves. It is, then, the idea of cause which introduces into the mind the idea of substance. But is substance nothing more than cause which manifests it? .... The causative power is the essential attribute of substance; it is not substance itself. In a word, it has seemed to us surer to hold to these two primitive notions; distinct, though inseparably united; one, which is the sign and manifestation of the other, this, which is the root and foundation of that.' {104} "One would think this sufficiently explicit for all who are not afflicted with the blindness that will not see." (P. 539.)