According to our mode of conceiving, defining and classifying essences by means of the abstract generic and differential grades of being which we apprehend in them, all essences, even physically simple essences, are conceived as logically and metaphysically composite. Moreover we speak and think of their generic and differential factors as “material” and “formal” respectively, after the analogy of the composition of corporeal or physically composite essences from the union of two really distinct principles, matter and form; the analogy consisting in this, that as matter is the indeterminate principle which is determined and actuated by form, so the _generic_ concept is the indeterminate concept which is made definite and specific by that of the _differentia_.(88) But when we think of the _genus_ of any corporeal essence as “material,” and the _differentia_ as “formal,” we must not consider these “metaphysical parts” as really distinct; whereas the “physical parts” of a corporeal substance (such as man) are really distinct. The genus (animal), although a metaphysical part, expresses the _whole essence_ (man) in an indeterminate way; whereas the “matter” which is a physical part, does not express the whole essence of man, nor does the soul which is also a physical part, but only both together. Not a little error has resulted from the confusion of thought whereby _genus_ and _differentia_ have been regarded as material and formal constitutives in the literal sense of those expressions. 14. CHARACTERISTICS OF ABSTRACT ESSENCES.—When we consider the essences of things not as actually existing, but as intrinsically possible—the abstract, metaphysical essences, therefore—we find that when as objects of our thought they are analysed into their simplest constituents and compared or related with themselves and with one another they present themselves to our minds in these relations as endowed with certain more or less remarkable characteristics. (_a_) In the first place, being abstract, they present themselves to the mind as being what they are independently of actual existence at any particular time or place. Their intelligibility is something apart from any relation to any actual time or place. Being intrinsically possible, they might exist at any time or place; but as possible, they are out of time and out of place—_detemporalized_ and _delocalized_, if we may be permitted to use such expressions.(89)