syllogism； namely； proceeding from the universal in the major
premiss （the moral principle）； through a minor premiss containing a
subsumption of possible actions （as good or evil） under the former； to
the conclusion； namely； the subjective determination of the will （an
interest in the possible practical good； and in the maxim founded on
it）。 He who has been able to convince himself of the truth of the
positions occurring in the Analytic will take pleasure in such
parisons； for they justly suggest the expectation that we may
perhaps some day be able to discern the unity of the whole faculty
of reason （theoretical as well as practical） and be able to derive all
from one principle； which； is what human reason inevitably demands； as
it finds plete satisfaction only in a perfectly systematic unity of
its knowledge。
If now we consider also the contents of the knowledge that we can
have of a pure practical reason； and by means of it； as shown by the
Analytic； we find； along with a remarkable analogy between it and
the theoretical； no less remarkable differences。 As regards the
theoretical； the faculty of a pure rational cognition a priori could
be easily and evidently proved by examples from sciences （in which； as
they put their principles to the test in so many ways by methodical
use； there is not so much reason as in mon knowledge to fear a
secret mixture of empirical principles of cognition）。 But； that pure
reason without the admixture of any empirical principle is practical
of itself； this could only be shown from the monest practical use
of reason； by verifying the fact； that every man's natural reason
acknowledges the supreme practical principle as the supreme law of his
will… a law pletely a priori and not depending on any sensible
data。 It was necessary first to establish and verify the purity of its
origin； even in the judgement of this mon reason； before science
could take it in hand to make use of it； as a fact； that is； prior
to all disputation about its possibility； and all the consequences
that may be drawn from it。 But this circumstance may be readily
explained from what has just been said； because practical pure
reason must necessarily begin with principles； which therefore must be
the first data； the foundation of all science； and cannot be derived
from it。 It was possible to effect this verification of moral
principles as principles of a pure reason quite well； and with
sufficient certainty； by a single appeal to the judgement of mon
sense； for this reason； that anything empirical which might slip
into our maxims as a determining principle of the will can be detected
at once by the feeling of pleasure or pain which necessarily
attaches to it as exciting desire； whereas pure practical reason
positively refuses to admit this feeling into its principle as a
condition。 The heterogeneity of the determining principles （the
empirical and rational） is clearly detected by this resistance of a
practically legislating reason against every admixture of inclination；
and by a peculiar kind of sentiment； which； however； does not
precede the legislation of the practical reason； but； on the contrary；
is produced by this as a constraint； namely； by the feeling of a
respect such as no man has for inclinations of whatever kind but for
the law only； and it is detected in so marked and prominent a manner
that even the most uninstructed cannot fail to see at once in an
example presented to him； that empirical principles of volition may
indeed urge him to follow their attractions； but that he can never
be expected to obey anything but the pure practical law of reason
alone。
The distinction between the doctrine of happiness and the doctrine
of morality； in the former of which empirical principles constitute
the entire foundation； while in the second they do not form the
smallest part of it； is the first and most important office of the
Analytic of pure practical reason； and it must proceed in it with as
much exactness and； so to speak； scrupulousness； as any geometer in
his work。 The philosopher； however； has greater difficulties to
contend with here （as always in rational cognition by means of
concepts merely without construction）； because he cannot take any
intuition as a foundation （for a pure noumenon）。 He has； however； this
advantage that； like the chemist； he can at any time make an
experiment with every man's practical reason for the purpose of
distinguishing the moral （pure） principle of determination from the
empirical； namely； by adding the moral law （as a determining
principle） to the empirically affected will （e。g。； that of the man who
would be ready to lie because he can gain something thereby）。 It is as
if the analyst added alkali to a solution of lime in hydrochloric
acid； the acid at once forsakes the lime； bines with the alkali；
and the lime is precipitated。 just in the same way； if to a man who is
otherwise honest （or who for this occasion places himself only in
thought in the position of an honest man）； we present the moral law by
which he recognises the worthlessness of the liar； his practical
reason （in forming a judgement of what ought to be done） at once
forsakes the advantage； bines with that which maintains in him
respect for his own person （truthfulness）； and the advantage after
it has been separated and washed from every particle of reason
（which is altogether on the side of duty） is easily weighed by
everyone； so that it can enter into bination with reason in other
cases； only not where it could be opposed to the moral law； which
reason never forsakes； but most closely unites itself with。
But it does not follow that this distinction between the principle
of happiness and that of morality is an opposition between them； and
pure practical reason does not require that we should renounce all
claim to happiness； but only that the moment duty is in question we
should take no account of happiness。 It may even in certain respects
be a duty to provide for happiness； partly； because （including
skill； wealth； riches） it contains means for the fulfilment of our
duty； partly； because the absence of it （e。g。； poverty） implies
temptations to transgress our duty。 But it can never be an immediate
duty to promote our happiness； still less can it be the principle of
all duty。 Now； as all determining principles of the will； except the
law of pure practical reason alone （the moral law）； are all
empirical and； therefore； as such； belong to the principle of
happiness； they must all be kept apart from the supreme principle of
morality and never be incorporated with it as a condition； since
this would be to destroy all moral worth just as much as any empirical
admixture with geometrical principles would destroy the certainty of
mathematical evidence； which in Plato's opinion is the most
excellent thing in mathematics； even surpassing their utility。
Instead； however； of the deduction of the supreme principle of
pure practical reason； that is； the explanation of the possibility
of such a knowledge a priori； the utmost we were able to do was to
show that if we saw the possibility of the freedom of an efficient
cause； we should also see not merely the possibility； but even the
necessity； of the moral law as the supreme practical law of rational
beings； to whom we attribute freedom of causality of their will；
because both concepts are so inseparably united that we might define
practical freedom as independence of the will on anything but the
moral law。 But we cannot perceive the possibility of the freedom of an
efficient cause； especially in the world of sense； we are fortunate if
only we can be sufficiently assured that there is no proof of its
impossibility； and are now； by the moral law which postulates it；
pelled and therefore authorized to assume it。 However； there are
still many who think that they can explain this freedom on empirical
principles； like any other physical faculty； and treat it as a
psychological property； the explanation of which only requires a
more exact study of the nature of the soul and of the motives of the
will； and not as a transcendental predicate of the causality of a
being that belongs to the world of sense （which is really the
point）。 They thus deprive us of the grand revelation which we obtain
through practical reason by means of the moral law； the revelation；
namely； of a supersensible world by the realization of the otherwise
transcendent concept of freedom； and by this deprive us also of the
moral law itself； which admits no empirical principle of
determination。 Therefore it will be necessary to add something here as
a protection against this delusion and to exhibit empiricism in its
naked superficiality。
The notion of causality as physical necessity； in opposition to
the same notion as freedom； concerns only the existence of things so
far as it is determinable in time； and； consequently； as phenomena； in
opposition to their causality as things in themselves。 Now if we
take the attributes of existence of things in time for attributes of
things in themselves （which is the mon view）； then it is impossible
to reconcile the necessity of the causal relation with freedom； they