The _second_ requirement, which is derivable from this first, demands of the content of art that it should not be anything abstract in itself. This does not mean that it must be concrete as the sensuous is concrete in contrast to everything spiritual and intellectual, these being taken as in themselves simple and abstract. For everything that has genuine truth in the mind as well as in nature is concrete in itself, and has, in spite of its universality, nevertheless, both subjectivity and particularity within it. If we say, _e.g._, of God that he is simply _One_, the supreme Being as such, we have only enunciated a lifeless abstraction of the irrational understanding. Such a God, as he himself is not apprehended in his concrete truth, can afford no material for art, least of all for plastic art. Hence the Jews and the Turks have not been able to represent their God, who does not even amount to such an abstraction of the understanding, in the positive way in which Christians have done so. For God in Christianity is conceived in His truth, and therefore, as in Himself thoroughly concrete, as a person, as a subject,[133] and more closely determined, as mind or spirit. What He is as spirit unfolds itself to the religious apprehension as the Trinity of Persons, which at the same time in relation with itself is _One_. Here is essentiality, universality, and particularity, together with their reconciled unity; and it is only such unity that constitutes the concrete. Now, as a content in order to possess truth at all must be of this concrete nature, art demands the same concreteness, because a mere abstract universal has not in itself the vocation to advance to particularity and phenomenal manifestation and to unity with itself therein.