Page:Ferrier's Works Volume 1 - Institutes of Metaphysic (1875 ed.).djvu/330

302PROP. XII.———— counter-propositions, which reduce to logical precision the vague and uncertain utterances of psychology on this subject, and which, if true, will be sufficient to uphold matter per se as thinkable, notwithstanding the demonstration of Proposition IV., by which it was proved to be absolutely unknowable.

2. In considering this proposition and its demonstration,—the first circumstance to be attended to is this—that matter and its qualities per se may very well be thought of, if some additional element be not essential to their original cognition. Thought can subtract whatever is not absolutely necessary to constitute knowledge in the first instance; but thought cannot do more than this. No power of abstraction can withdraw from representation any element indispensable to the composition of presentation. Every other element may be withdrawn, but an indispensable element way not be withdrawn. This point was sufficiently explained in the preceding proposition (Obs. 5), where the limitation of thought now referred to was called restriction by the way of subtraction.

3. The question therefore is, In attempting to cogitate matter and its qualities per se, is thought leaving out, or endeavouring to leave out, any element essential to the original cognition of matter