A sustained philosophical defense and elaboration of a metaphysical system that treats reality as representation perceived by the intellect yet ultimately grounded in an underlying will. It opens with a polemical critique of Kant, then supplies extended discussions of perception, the senses, and a priori knowledge; develops distinctions between perceptual and abstract cognition; examines the limits and failings of the intellect, association of ideas, logic, rhetoric, and scientific and mathematical method; considers practical reason and Stoicism; and adds chapters on the possibility of knowing the thing in itself, the primacy of the will in self-consciousness, and the objectification of will in animal organisms.