The Ideal doesn’t exist except as a concept. It points to an absence, to nothing in the world we inhabit. If one attends to the material world, our relationships to it, and to one another, we will be confronted in every waking second with the aporia of an ever changing realty, one that needs no “ideal” hovering over it to fill us with wonder and the mystery (and the misery) of existence.
The concept of the Ideal is partner to that of Immutability–the longing for that which does not change. Without that–without the longing for immutability, the Ideal, and the idea of perfection, has no meaning. This is where Modernism parts from the Romantic. That is the metaphysics behind the aesthetic.