One may say that Plato’s theory of ideas was a metaphysical presentation of the universe, sounding in conceptions of reality. But for the Middle Ages, the problem whether genera and species exist when abstracted from their particulars, sprang from logical controversy. It was a problem of cognition, cognizance, understanding: how should one understand and analyze the contents of a statement, _e.g._ Socrates is a man. Moreover, it was a fundamental and universal problem of cognition; for it was not merely occupied, like all mental processes, with bringing data to consistent formulation, but pertained to those processes themselves by which any and all data are stated or formulated. It touched every formulation of truth, asking, in fine, how are we to think our statements? The philosophers of the eleventh and twelfth centuries, however, did not view this problem as one pertaining to the mind’s processes, and as having to do solely with the understanding of the contents of a statement. Rather, even as Plato had done, they approached it as if it were a problem of modes of existence; and for this very reason it had pushed Roscellin into theological error. The discussion was to pass through various stages; and each stage may seem to us to represent the point reached by the thinker in his analysis of his conscious meaning in stating a proposition. Moreover, each solution may be valid for him who gives it, because of its correspondence to the meaning of his utterances so far as he has analyzed them. But mediaeval men could not take it in this way. Their intellectual task lay in appropriating, and in their own way re-expressing, all that had come to them from an authoritative past. The problem of universals had been stated by a great authority, who put it as pertaining to the objective reality of genera and species. How then might mediaeval men take it otherwise, especially when at all events it pertained in all verity to their endeavour to grasp and re-express the contents of transmitted truth? It became for a while the crucial problem, the answer to which might indicate the thinker’s general intellectual attitude. Far from keeping to logic, to the _organon_ or instrumental part of the mediaeval endeavour to know, it wound itself through metaphysics and theology. Obviously the thinker’s answer to the problem would bear relation to his thoughts upon the transcendent reality of spiritual essences.