Practically this metaphysical science--which is so called as dealing with a province or provinces of being _beyond_ the ordinary or natural _(physical)_ realities--treated God and the Soul by the same terms (or _categories_) as it used in dealing with 'material' objects. God e. g. was a force, a cause, a being; so, too, was the Soul. The main butt of Kant's destructive _Criticism of pare Reason_ is to challenge the justice of including God and the Soul among the objects of science,--among the things we can know as we may know plants or stars. To make an object of knowledge (in the strict sense), to make a thing, the prerequisite, Kant urges, is perception in space and time. Without a sensation--and that sensation, as it were, laid out in place and duration--an object of science is impossible. No mere demonstration will conjure it into existence. And with that requirement the old theology and psychology, which professed to expound the object-God and the object-soul, were ruled out-of-order in the list of sciences, and reduced to mere dialectical exercises. The circle of the sciences, therefore, does not lead beyond the conditioned,' beyond the regions of space and time. It has nothing to say of a 'first cause' or of an ultimate end.
Such was the result that might fairly be read from Kant's _Criticism of pare Reason_,--especially if read without its supplementary sequels, and, above all, if read by those in whom feeling was stronger than thought, or who were by nature more endowed with the craving for faith than with the mind of philosophy. Such a personality appeared in J. H. Jacobi, the younger brother of a poet not undistinguished in his day. Amid the duties of public office and the cares of business, he found time to study Spinoza, the English and Scotch moralists, and above all to follow with interest the development of Kant from the year 1763 onwards. His house at Düsseldorf was the scene of many literary reunions, and Jacobi himself maintained familiar intercourse with the leaders of the literary and intellectual world, such as Lessing, Hamann, Goethe. His first considerable works were two novels, in letters,--Allwill, begun in a serial magazine in 1775, and Woldemar, begun in another magazine in 1777; both being issued as complete works in 1781. Both turn on a moral antithesis, and both leave the antithesis as they found it. _Here_ pleads the advocate of the heart: 'it is the heart which alone and directly tells man what is good': 'virtue is a fundamental instinct of human nature': the true basis of morals is an immediate certainty; and the supreme standard is an 'ethical genius' which as it were discovered virtue and which still is a paramount authority in those exceptional situations in life when the 'grammar of virtue' fails to supply adequate rules, and where, therefore, the immediate voice of conscience must in a 'licence of sublime poesy[5]' dare, as Burke says, to 'suspend its own rules in favour of its own principles.' _There_, on the other hand, is the champion of reason, who declares all this sentimentalism 'a veritable mysticism of antinomianism and a quietism of immorality[6]': 'To humanity,' he says, 'and to every man (every complete man) principles, and some system of principles, are indispensable.' Woldemar concludes with the pair of mottoes: 'Whosoever trusts to his own heart is a fool,' and 'Trust love: it takes everything, but it gives everything.'