In Book I of his Prolegomena, "Metaphysics of Knowledge', Green comes across as a somewhat heavy-handed idealist; however, in Book II, "The Will', he develops an original transcendental analysis of human nature. I shall refer to his theory of "the will' as the theory of "human practice'. Green's claim, that in all his desires an agent pursues an idea of himself, represents, on analysis, a transcendental rule of human practice. Green takes Kantian transcendentalism and develops it further. Kant had established a rigid dichotomy between pure thinking, on the one hand, and experience, on the other. Thus Kantian transcendentalism asserts the formative role of pure, a priori categories and denies transcendental status to all human faculties other than thinking. Green's philosophy takes the transcendental idea and develops it by offering a better explanation of the mental setting that creates the format for human practice. According to Green, human behaviour is not preconditioned by our instincts or natural forces, but by an interplay of "will', "thought' and "desire' — an interplay that can be rendered in a formula.