It is in the way now described that we form genera, and species, and the various classes into which, for purposes of science, we divide the multitude of objects which are presented in nature, and which, but for this faculty, would appear to us but a confused and chaotic assemblage without number, order, or arrangement. The individuals exist in nature--not the classes, and orders, and species: these are the creations of the human mind, conceptions of the brain, results of that process of thought now described as the reflective faculty in its synthetic form. _Importance of this Process._--It is evident at a glance that this process lies at the foundation of all science. Had we no power of generalization--had we no power of separating, in our thoughts, the quality from the substance to which it pertains, of going beyond the concrete to the abstract, beyond the particular to the general--could we deal only with individual existences, neither comparison nor classification would be possible; each particular individual object would be a study to us by itself, nor would any amount of diligence ever carry us beyond the very alphabet of knowledge. _Existence of general Conceptions questioned._--Important as this faculty may seem when thus regarded, it has been questioned by some whether, after all, we have, in fact, or can have, any general abstract ideas; whether triangle, man, animal, etc., suggest in reality any thing more to the mind than simply some particular man, or triangle, or animal, which we take to represent the whole class to which the individual belongs. There can be no question, however, that we do distinguish in our minds the thought of some particular man, as Mr. A, or some particular sort of man, as black man, white man, from the thought suggested by the term man; and the thought of an isosceles or right-angled triangle, from the thought suggested by the unqualified term triangle. They do not mean the same thing; they have not the same value to our minds. Now there are a great multitude of such general terms in every language, they have a definite meaning and value, and we know _what_ they mean. It must be then that we have general abstract ideas, or general conceptions.