The fundamental doctrine of both the schools of nescience is the relativity of human knowledge, and that doctrine as taught by the Scottish psychologists (and notably by Scotland's greatest metaphysician since Hume, Sir William Hamilton) has been wrested out of their hands, and turned against the theism they also advocate. Mr. Spencer would exhibit them all as 'hoist with their own petard.' It is necessary, therefore, to enquire whether this doctrine of relativity favours a theory of nescience, or warrants a counter-doctrine of the knowledge of the infinite, or is indifferent to both. With us the relativity of knowledge is a first principle in philosophy. But to affirm it, is merely to assert that all that is known occupies a fixed relation to the knower. It is to affirm nothing as to the character or contents of his knowledge. As regards the objects known we further maintain that they are apprehended only in their differences and contrasts. We know self only in its contrast with what is not self, a particular portion of matter only in its relation to other portions which surround and transcend it. So also and for the same reason, with the finite and the infinite. The one is not a positive notion, and the other negative; the one clear, and the other obscure. Both are equally clear, both sharply defined, so far as they are given us in relation. If the one notion suffers, the other suffers with it. In short, if we discharge any notion from all relation with its opposite or contrary, it ceases to be a notion at all. The finite, if we take it alone, is as inconceivable as the infinite, if we take it alone; phenomena by themselves are as incogitable as substance by itself: and the relative as a notion cut off from the absolute which antithetically bounds it, is not more intelligible than the absolute as an essence absolved from all relations. And thus the entire fabric of our knowledge being founded on contrasts, and arising out of differences, involving in its every datum another element hidden in the background, may be said to be a vast double chain of relatives mutually complementary. It looks ever in two directions, without and within, above and beneath, before and after.