The weapon of criticism obviously cannot replace the criticism of weapons. Material force can only be overthrown by material force, but theory itself becomes a material force when it has gripped the masses. Theory is capable of gripping the masses when it demonstrates ad hominem, and it demonstrates ad hominem, when it becomes radical. To be radical is to grasp things by the root, but for man the root is man himself. The clear proof of the radicalism of German theory, and hence of its political energy, is that it proceeds from the decisive positive abolition of religion.