Türcke's book exposes the concept of didactic mediation as a decline of the metaphysical, which once sought to clarify the relationship between ideas and the sensory world, form and matter, God and the world. Through Plato, Aristotle, and the ancient doctrine of the Trinity, it is shown how, under the conditions of philosophical idealism, mediation inevitably becomes the Absolute, and thus threatens to collapse into a mediation of nothing with nothing.