In a certain way--vital enough, too--"things in themselves" _are_ "unknown and unknowable." Man is a small, dependent, limited being. Let us admit at once every old proverb in the world, to the effect that "the finite cannot comprehend the infinite." Sir William Hamilton issued a tedious list of such proverbs. Let us adopt the whole of it. "The finite cannot comprehend the infinite." The very meaning of "things in themselves" is that they are withheld from us in their _specific contents_. But in their _general nature_ they are related and revealed to us; and the revelation is always asserted when we name them "source of impact," the "real correlate of matter," "things in themselves," or even "the unknown and unknowable." Is there an "unknown and unknowable?" Yes, there _is_. But whatever _is_ has _being_--_must_ have being, or not be that which "is." So much then we _know_ of "the unknown and unknowable"; it has being; it is a _fact_. But we know it negatively, as well as positively. We know what it is _not_, on precisely the same ground that we know what it _is_. Being a "noumenon," it is _not_ a phenomenon; being a "thing in _itself_," it is not what things are to _us_. Being "the real correlate of matter," it is _not_ matter, but is the objective background of matter. But _now_: Kant had analyzed matter and found it to be a _relation_--a relation between finite subjective awareness and this very noumenal background now in evidence. He had found, too, that all _matter_--every spicule of it--is _exhausted in the relation_. He had found that, out of the relation, _matter has no existence_. By these presents, then, we know that the objective background of matter, the ultimate non-ego, is _not material_. And, at this point, where are we, if we pause and think? When reduced to elements, to principles, what is there of the universe--the all of things? Just the subjective and the objective, mind and matter. Hence, that which is _not matter_ is _mind_. Nothing else is left for it.