the
one case the method is synthetic, in the other it is analytic. It is the
function of mathematics to connect and compare clear and certain concepts
of quantity in order to draw conclusions from them; the function of
philosophy is to analyze concepts given in a confused state, and to make
them detailed and definite. Philosophy has also this disadvantage, that
it possesses very many undecomposable concepts and undemonstrable
propositions, while mathematics has only a few such. "Philosophical truths
are like meteors, whose brightness gives no assurance of their permanence.
They vanish, but mathematics remains. Metaphysics is without doubt the most
difficult of all human sciences _(Einsichten)_, but a metaphysic has
never yet been written"; for one cannot be so kind as to "apply the term
philosophy to all that is contained in the books which bear this title." In
the closing paragraphs, on the ultimate bases of ethics, the stern features
of the categorical imperative are already seen, veiled by the English
theory of moral sense, while the attractive _Observations on the Feeling
of the Beautiful and the Sublime_, which appeared in the same year, still
naively follow the empirical road.

The empirical phase reaches its skeptical termination in the satire _Dreams
of a Ghost-seer explained by the Dreams of Metaphysics_, 1766, which pours
out its ingenious sarcasm impartially on spiritualism and on the assumed
knowledge of the suprasensible. Here Kant is already clearly conscious of
his new problem, a theory of the limits of human reason, conscious also
that the attack on this problem is to be begun by a discussion of the
question of space. This second question had been for many years a frequent
subject of his reflections;[1] and it was this part of the general critical
problem that first received definitive solution. In the Latin dissertation
_On the Form and Principles of the Sensible and Intelligible World_, 1770,
which concludes the pre-critical period, and which was written on the
occasion of his assumption of his chair as ordinary professor, the
critique of sensibility, the new theory of space and time, is set forth in
approximately the same form as in the _Critique of Pure Reason_, while the
critique of the understanding and of reason, the theory of the categories
and the Ideas and of the sphere of their validity, required for its
completion the intellectual labor of several more years. For this essay,
_De Mundi Sensibil