It is necessary, however, not to convert these distinctions of the concept into abstractions: by approximation, and for a practical purpose, we can speak of a given action as a theoretical or practical one, an economic or moral one. In fact, in every fragment of reality we find the universal, and therefore all the forms of the universal. But on the other hand it is impossible to think any concrete datum, and to recognize it as an affirmation of the spirit as a whole, unless we distinguish each of its aspects in the most rigorous fashion. We shall then have a criticism of art and poetry, from the æsthetic point of view; or of philosophy, from the logical one; and a moral judgment which takes into account only the individual moral initiative. The distinctions of the concept are then used as directing principles of thought, but not, in the way empirical concepts are used, as criteria for a classification of objects; nor, again, as characteristics of epochs of actual historical development, which in the end reduce themselves to types of material classification. Croce's theory of the unity and distinctions of the concept coincides with the old division of concepts into universal, particular, and singular ones. The true logical definition is reached only by determining the singularity of a distinction in relation with the other distinctions (particularity), and with the whole (universality). For instance, the concept of beauty is intuition (singularity), knowledge (particularity), and finally spirit or mind (universality). The symbol corresponding to this peculiar relation is not that of a fine or succession, but of a circle: there is not a first and a last term of the series, a beginning and an end, but a perpetual revolution, in which every distinction in turn may appear as the beginning and the end of the series. Art or philosophy, knowledge or action, may be postulated with equal reason as the end of the spirit: the true end, however, is not any of the particular forms, but only the spirit or mind or reality as a whole.