Page:Ferrier's Works Volume 1 - Institutes of Metaphysic (1875 ed.).djvu/225

PROP. VII.————

ever it knows anything at all (by Prop. I.): in other words, no cognition, in which one does not apprehend oneself, is possible. Therefore the ego or oneself is known as the element common to all cognition—that is, as the summum genus of cognition. Again, it is not a necessary truth of reason that matter must be known whenever anything at all is known: in other words, cognitions in which no material element is apprehended, are, if not actual, at any rate possible and conceivable. No contradiction is involved in that supposition; and, therefore, matter is not known as the element common to all cognition, but only as the element peculiar to some cognitions—that is, as the differential part of some cognitions. And hence the ego is the unchangeable, necessary, and universal part of cognition, while matter, in all its varieties, is only a portion (not the whole) of the changeable, contingent, and particular part of cognition.

OBSERVATIONS AND EXPLANATIONS.

Why this Proposition is introduced.1. Although this proposition is, in its first clause, a mere repetition of Proposition I., its introduction is necessary, in order to mark distinctly what the elements are which enter into the constitution of knowledge. It is not enough to show, as was done in the immediately preceding proposition, that every