Certain problems of Logic, not yet solved in a satisfactory manner, arise from the failure to make clear the confusion between concepts and pseudoconcepts, and between empirical and abstract concepts. Is it or is it not true that every concept must have an individual representation, taken from its own sphere, as a necessary _support_? Are concepts of _things_ possible, or is there a special concept corresponding to every thing? Is a concept of the _individual_ possible? These three questions may be answered in the affirmative, in the negative, and in the affirmative-negative, according as they are referred to the empirical concept, the abstract concept, or the pure concept. [Sidenote: _The representative accompaniment of the concept._] For, if we consider the first question, we must resolutely deny that the abstract concept has any need of a particular representation as its necessary support. The geometric triangle, as such, is neither white nor black, nor of any given size; if the representation of a particular triangle unites itself to it, geometry discards it. But we must just as resolutely affirm than an empirical or representative concept has always an image to support it; the concept of a cat needs the image of a cat, and every book on zoology is accompanied with illustrations. The image may be varied, but never suppressed; and it may be varied only within certain limits, because, if these be exceeded, the concept itself loses its form and is dissipated. Thus, for the concept of the cat, we could frame a representation of a white or black or red cat, or a small or big one; but if scarlet colour or the size of an elephant be attributed to the cat, which serves as symbol of the fiction, the concept must be changed. That concept has at its command the images of cats, upon which it has been formed, which, as we know, are always finite in number. Finally, with reference to the pure concept, it must be said that every image and no image is in turn a symbol of it; as every blade of grass (as Vanini said) represents God, and a number of images, however great it be, does not suffice to represent Him. [Sidenote: _The concept of the thing and the concept of the individual._]