Hence the scholastic formulæ: _Ens et unum convertuntur_, and _Omne ens est unum_. The truth embodied in these is so self-evident that the expression of it may seem superfluous; but they are not mere tautologies, and in the interests of clear and consistent thinking our attention may be profitably directed to them. The same remark applies to much in the present and subsequent chapters on the transcendental attributes of being. 27. KINDS OF UNITY.—(_a_) The unity we have been describing has been called _transcendental_, to distinguish it from _predicamental_ unity—the unity which is proper to a special category of being, namely, _quantity_, and which, accordingly, is also called _quantitative_ or _mathematical_ unity. While the former is common to all being, with which it is really identical, and to which it adds nothing real, the latter belongs and is applicable, properly speaking, only to the mode of being which is corporeal, which exists only as affected by quantity, as occupying space, as capable of measurement; and therefore, also, this latter unity adds something real to the being which it affects, namely, the attribute of quantity, of which unity is the measure and the generating principle.(136) For quantity, as we shall see, is a mode of being really distinct from the corporeal substance which it affects. The quantity has its own transcendental unity; so has the substance which it quantifies; so has the composite whole, the quantified body, but this latter transcendental unity, like the composite being with which it is identical, is not a _unum per se_ but only a _unum per accidens_ (_cf._ _b_, _infra_). We derive our notion of quantitative or mathematical unity, which is the principle of counting and the standard of measuring, from dividing mentally the continuous quantity or magnitude which is one of the immediate data of sense experience. Now the distinction between this unit and transcendental unity supposes not merely that quantity is really distinct from the corporeal substance, but also that the human mind is capable of conceiving as real certain modes of being other than the corporeal, modes to which quantitative concepts and processes, such as counting and measuring, are not _properly_ applicable, as they are to corporeal reality, but only in an _analogical_ or _transferred_ sense (2). The notion of transcendental unity, therefore, bears the same relation to that of quantitative unity, as the notion of being in general bears to that of quantified or corporeal being.