Page:Ferrier's Works Volume 1 - Institutes of Metaphysic (1875 ed.).djvu/441

RhPROP. III.———— 1. This is the most important proposition in the agnoiology: indeed, with the exception of the first of the epistemology, it is the most fruitful and penetrating proposition in the whole system. It announces—for the first time, it is believed—the primary law of all ignorance, just as the first of the epistemology expresses the primary law of all knowledge. It is mainly by the aid of these two propositions that this system of Institutes is worked out. All the other propositions have an essential part to play in contributing to the final result; but these two are the most efficient performers in the work. If the reader has got well in hand these two truths—first, that there can be a knowledge of things only with the addition of a self or subject; and, secondly, that there can be an ignorance only of that of which there can be a knowledge—he will find himself in possession of a lever powerful enough to break open the innermost secresies of nature. These two instruments cut deep and far—they lay open the universe from stem to stern.

2. The law of all ignorance may be illustrated by the same symbols which were used in Proposition IV. of the epistemology, Obs. 11, to illustrate the law of all knowledge. Just as there can be a knowledge of X only when there is a knowledge of Y, so there can be an ignorance of X only when there is an ignorance of Y. Because if there could be an ignorance of X without Y, but not a knowledge of X without Y, something would be ignored