What are called the metaphysical grades of being, those positive moments of perfection or reality which the mind detects in the individual, as, for instance, substantiality, materiality, organic life, animality, rationality, individuality, in the individual man—whether we describe them as “phases” or “aspects” or “formalities” of being—are undoubtedly distinct objects for abstract thought. Why does it thus distinguish between them, and express them by distinct concepts, even when it finds them embodied in a single individual? Because, reflecting on the manner in which reality presents itself, through sense experience, as actually existing, it finds resemblances and differences between individually distinct data. It finds in some of them grades of reality which it does not find in others, individual, specific, and generic grades; and some—transcendental—grades common to all. Now between these various grades of being as found in one and the same individual it cannot be denied that there exists a logical distinction with a foundation or ground for it in the individual reality; because the latter, _being more or less similar_ to other individual realities, causes the mind to apprehend it by a number of distinct concepts: the individuality whereby it differs really from all other individuals of the same species; the specific, differential and generic grades of being whereby it is conceptually identified with wider and wider classes of things; and the transcendental grades whereby it is conceptually identified with all others. The _similarity_ of really distinct individuals, which is the _conceptual identity_ of their _qualities_, is the ground on which we conceptually identify their _essences_. Now is there any reason for thinking that these grounds of similarity, as found in the individual, are _really distinct_ from one another in the latter? They are certainly conceptually distinct expressions—each less inadequate than the wider ones—of what is really one individual essence. But we must take them to be all really identical in and with this individual essence, unless we are prepared to hold conceptual plurality as such to be real plurality; in which case we should also hold conceptual unity as such to be real unity. But this latter view is precisely the error of extreme realism, of reifying abstract concepts and holding the “_universale a parte rei_”: a theory which leads logically to monism.(143)