Spinozism as the only rational system, indeed as the last word of all speculative metaphysics; for them logical thought necessarily led to pantheism and determinism.  In France, after reaching its climax in Voltaire, it ended in materialism, atheism, and fatalism; and in England, where it had developed the empiricism of Locke, it came to grief in the scepticism of Hume.  If we can know only our impressions, then rational theology, cosmology, and psychology are impossible, and it is futile to philosophize about God, the world, and the human soul.  Consistently carried out, the logical-mathematical method seemed to land the intellect in Spinozism or in materialism—­in either case to catch man in the causal machinery of nature.  In this dilemma many were tempted to throw reason overboard as an instrument of ultimate truth, and to seek for certainty through other functions of the human soul—­in feeling, faith, or mystical vision of some sort; the claims of the heart and will were urged against the proud pretensions of the intellect (Hamann, Herder, Jacobi).  Another way of escape was found by substituting the organic conception of reality for the logical-mathematical view of the Aufklaerung; nature and life, poetry, art, language, political, social, and religious institutions are not creations of reason, not things made to order, but organic—­products of evolution (Lessing, Herder, Winckelmann, Goethe).  Man, himself, moreover, is not mere intellect, but a being in whom feelings, impulses, yearnings, will, are elements to be reckoned with.  And reality is not as transparent as the Enlightenment assumed it to be; existence divided by reason leaves a remainder, as Goethe had put it.

It was Immanuel Kant who tried to arbitrate between the conflicting tendencies of his age.  He was an Aufklaerer in so far as he brought reason itself to the bar of reason and sat in judgment upon its claims, and, likewise, in so far as he insisted on the objective validity of physics and mathematics.  But he was as much opposed to the pretentiousness of dogmatic metaphysics as to the pusillanimity of scepticism and the Schwaermerei of mysticism.  He repudiated the shallow proofs of the existence of God, freedom, and immortality no less emphatically than he rejected materialism with its atheism, fatalism, and hedonism.  He tried to save everything worth saving—­rational knowledge, modern science, the basal truths of the old metaphysics, and the most precious human values.  For the scientific intelligence, so he held, nature and the self are absolutely determined; every physical occurrence and every human act are necessary links in a causal chain.  But such knowledge is possible only in the field of phenomena (Erscheinungen); through sense-perception and the discursive understanding we cannot reach the inner core of reality; nor can we pierce the veil of appearances by means of intellectual intuitions, mystical visions, feeling, or faith, i.e.,