not have me establish a doctrine of ignorance which was not consistent with my doctrine of knowledge. Surely I am entitled to deduce all that is logically deducible from my principles. Your meaning I presume is that my doctrine of ignorance flows so manifestly from my doctrine of knowledge that it is unnecessary to develop and parade it. There I differ from you. It flows inevitably, but I cannot think that it flows obviously. Else why was it never hit upon until now?… Don't tell me, then, that my conclusions that matter per se, Ding an sich, is what it is impossible for us to be ignorant of, just because it is absolutely unknowable (and for no other reason). Don't tell me that this conclusion is so obvious as not to require to be put down in black and white, when we find Kant and every other philosopher drawing, but most erroneously, the directly opposite conclusion from the same premises. Matter per se, Ding an sich, was of all things that of which we were most ignorant!! and the ruin of metaphysics was the consequence of their infatuated blindness. Your objection, then, to my doctrine of ignorance, viz., that it is fixed in the very fixing of the doctrine of knowledge, and therefore does not require explication or elucidation, I cannot regard as a good objection. It is true that the one of these fixes the other; but it requires some amount of explanation and demonstration to make this palpable to the understandings even of the most acute, and I am not sure that even you (yes, put on your best pair of spectacles, you will need them) yet see how impossible it is for us to be ignorant of matter per se, or of anything which is absolutely unknowable.'
This matter of the Ding an sich Ferrier felt to be the crucial point in his system: 'You talk glibly of
