Founder of a Metaphysics of Morals 305Therefore, we must think of absolute space as a regulative idea of reason, or
so Kant claims.
Though Kant is a Newtonian as far as science is concerned, his project
of providing Newtonian physics with a metaphysical foundation indicates
a more Leibnizian bent of mind. Kant's contemporaries did not know what
to make of the book. Thus a review of the book that came out three years
after its first publication and two years after its second edition remarked with
some surprise that until then only one review of the work had appeared.^132
Johann Gottfried Karl Kiesewetter, one of Kant's students, noted as late
as 1795 that "hardly anyone" had bothered to work on the Metaphysical
Foundations of Natural Science.^133 The same might be said of Kant. As soon
as he finished writing the manuscript, he turned to other matters.^134
Kant's Intervention in the Pantheism Dispute:
For "Pure Rational Faith"In July 1780, Lessing admitted to Jacobi - at least according to Jacobi
(and only after Lessing's death in February of 1781) — that he was a Spin-
ozist.^135 Such an admission would have been risky, given that Spinoza was
thought to be a "satanic atheist," and his pantheistic theory was consid¬
ered a "monstrous hypothesis." If such an admission had become public,
Lessing would most certainly have been embroiled in the greatest contro¬
versy of his life. It would have proved that he was not a theist, and that his
rationalism had led him to deny the reality of a transcendent God. Jacobi
tried to use this and other information from his conversations with Less¬
ing to prove that he had understood the man better than some of his best
friends (who included Mendelssohn). Thus he began a correspondence
with Mendelssohn about Lessing's alleged Spinozism. Mendelssohn was
incredulous and, wanting to save his friend's good name, tried to convince
Jacobi that whatever Lessing had said, he could not have meant what Ja¬
cobi took him to mean. This correspondence remained private until 1785,
when Jacobi heard that Mendelssohn was about to publish sa book called
Morgenstunden (Morning Hours), in which he would also discuss the prob¬
lem of pantheism and thus respond to Jacobi's claims at least in an indi¬
rect way. Afraid that Mendelssohn would reveal their private controversy,
Jacobi decided to preempt him by publishing a book, On the Doctrine of
Spinoza in Letters to Mr. Mendelssohn, which also appeared in 1785 and
made public Lessing's alleged confession and Mendelssohn's private letters
to Jacobi.