knowledge of reality is inadequate, that it does not _comprehend_ all that is in the reality, but surely not that it is essentially illusory and of its very nature incapable of giving us any true and valid insight into the nature of reality. Fixing our attention on the virtual distinction we see that the mind is supposed by means of it to apprehend, through a plurality of distinct concepts, what it knows somehow or other to be _one_ being. Now if it knows the reality to be _really one_, it knows that the formal object of every distinct concept of this reality is really identical with the objects of all the other concepts of the latter. This condition of things is certainly verified when the mind can see that each of the distinct concepts, though not _explicitly_ presenting the objects of the others, nevertheless _implicitly and necessarily_ involves all these other objects:(156) for by seeing that the distinct concepts necessarily involve one another objectively it sees that the reality apprehended through all of them must necessarily be _one reality_. This is what takes place in the _imperfect_ virtual distinction: the concepts prescind from one another formally, not objectively. But suppose that the distinct concepts prescind from one another _objectively_, so that they cannot be seen by any analysis to involve one another even implicitly, but present to the mind, so far as they themselves are concerned, adequately distinct modes of being—as happens in the _perfect_ virtual distinction, _e.g._ between organic life, sentient life, and intellectual life (in man), or between animality and rationality (in man),—then the all-important question arises: How do we know, in any given case of this kind, whether or not these adequately distinct thought-objects are _identical with one another in the reality_? What is the test for determining whether or not, in a given case, these objects, which are _many_ for abstract intellectual thought, are _one being_ in the real order? The answer seems to be that _internal and external sense experience_ can and does furnish us with embodiments of these intellectual manifolds,—embodiments each of which we apprehend as _a being that is really one_, as an _individual subject_ of which they are conceptually distinct predicates.