The ordinary logic-books have made us all familiar with the popular distinction between Abstract and Concrete. By a concrete term they mean the name of an existence or reality which is obvious to the senses, and is found in time and place;--or they mean the name of an attribute when we expressly or tacitly recognise its dependence upon such a thing of the senses. When, on the contrary, the attribute is forcibly withdrawn from its context and made an independent entity in the mind, the term expressing it becomes in the usual phraseology abstract. Any term therefore which denotes a non-sensible or intelligible object would probably be called abstract. And there is something to be said for the distinction, which, though unsuccessful in its expression, has some feeling of the radical antithesis between mere being and mere thought. It is true, that in the totality of sense and feeling, in the full sense-experience, there is a concrete fulness, as it were, an infinite store of features and phases waiting for subsequent analysis to detect. In the real kind of actual nature there is an inexhaustible mine of properties, which no artificial classification and description can ever come to the end of. Every quality which we state, every relation which we predicate, is a partial and incomplete element in this presupposed reality, this implicit concrete; and as such is abstract, and comparatively unreal. It is something forcibly torn out of and held apart from its context. But on the other hand the concrete reality is not at first real, but implicit: it becomes really concrete only as it re-embraces, and re-constitutes in its totality the elements detected by analysis. But the popular distinction forgets this, and gives the title and rank of concrete to what very poorly deserves the name, viz. to the yet undiscerned reality denoted by a substantive name. Yet there can be little doubt that the popular use of these terms, or the popular apprehension of what constitutes reality,--for that is what it comes to,--is sufficiently represented by the ordinary logic-books. So that, if the whole business of the logician lies in formulating the distinctions prevalent in popular thought, the ordinary logic is correct.