To define abstract art, which occupies such an important place in contemporary aesthetics, merely as a plastic mode of expression that makes no attempt to seek its own forms among those already existing in reality is to give a very inadequate notion of it. The term “non-figurative art,” which is sometimes used to describe it, arbitrarily restricts its range by stressing as peculiar to it this elementary fact alone and by characterizing abstract art solely as a controversial or even as a revolutionary art, as opposed to traditional aesthetics, which is itself figurative. Abstract art at times has also been called “concrete” or “non-objective” art. All these definitions have as little validity in themselves as those that are made use of in the history of art and are acceptable only at their “face value,” to use the monetary term, because they have no absolute value but merely a conventional one based on the principle of exchange (Baroque, Gothic, Rococo, Cubist). However, they are not to be ignored, since they do express the state of uncertainty, uneasiness, and indecision that afflicts most amateurs and even historians of art in regard to abstract art. At the same time, these definitions also indicate an awareness that we are dealing with a very important and complex phenomenon, enriched by extensive projections into the domain of social psychology, sociology, and probably even metaphysics.