the rest； and that it would therefore be reasonable to ascribe all
possible perfections to the Author of the world； but these are not
strict logical inferences in which we can pride ourselves on our
insight； but only permitted conclusions in which we may be indulged
and which require further remendation before we can make use of
them。 On the path of empirical inquiry then （physics）； the
conception of God remains always a conception of the perfection of the
First Being not accurately enough determined to be held adequate to
the conception of Deity。 （With metaphysic in its transcendental part
nothing whatever can be acplished。）
When I now try to test this conception by reference to the object of
practical reason； I find that the moral principle admits as possible
only the conception of an Author of the world possessed of the highest
perfection。 He must be omniscient； in order to know my conduct up to
the inmost root of my mental state in all possible cases and into
all future time； omnipotent； in order to allot to it its fitting
consequences； similarly He must be omnipresent； eternal； etc。 Thus the
moral law； by means of the conception of the summum bonum as the
object of a pure practical reason； determines the concept of the First
Being as the Supreme Being； a thing which the physical （and in its
higher development the metaphysical）； in other words； the whole
speculative course of reason； was unable to effect。 The conception
of God； then； is one that belongs originally not to physics； i。e。；
to speculative reason； but to morals。 The same may be said of the
other conceptions of reason of which we have treated above as
postulates of it in its practical use。
In the history of Grecian philosophy we find no distinct traces of a
pure rational theology earlier than Anaxagoras； but this is not
because the older philosophers had not intelligence or penetration
enough to raise themselves to it by the path of speculation； at
least with the aid of a thoroughly reasonable hypothesis。 What could
have been easier； what more natural； than the thought which of
itself occurs to everyone； to assume instead of several causes of
the world； instead of an indeterminate degree of perfection； a
single rational cause having all perfection？ But the evils in the
world seemed to them to be much too serious objections to allow them
to feel themselves justified in such a hypothesis。 They showed
intelligence and penetration then in this very point； that they did
not allow themselves to adopt it； but on the contrary looked about
amongst natural causes to see if they could not find in them the
qualities and power required for a First Being。 But when this acute
people had advanced so far in their investigations of nature as to
treat even moral questions philosophically； on which other nations had
never done anything but talk； then first they found a new and
practical want； which did not fail to give definiteness to their
conception of the First Being： and in this the speculative reason
played the part of spectator； or at best had the merit of embellishing
a conception that had not grown on its own ground； and of applying a
series of confirmations from the study of nature now brought forward
for the first time； not indeed to strengthen the authority of this
conception （which was already established）； but rather to make a
show with a supposed discovery of theoretical reason。
From these remarks； the reader of the Critique of Pure Speculative
Reason will be thoroughly convinced how highly necessary that
laborious deduction of the categories was； and how fruitful for
theology and morals。 For if； on the one hand； we place them in pure
understanding； it is by this deduction alone that we can be
prevented from regarding them； with Plato； as innate； and founding
on them extravagant pretensions to theories of the supersensible； to
which we can see no end； and by which we should make theology a
magic lantern of chimeras； on the other hand； if we regard them as
acquired； this deduction saves us from restricting； with Epicurus； all
and every use of them； even for practical purposes； to the objects and
motives of the senses。 But now that the Critique has shown by that
deduction； first； that they are not of empirical origin； but have
their seat and source a priori in the pure understanding； secondly；
that as they refer to objects in general independently of the
intuition of them； hence； although they cannot effect theoretical
knowledge； except in application to empirical objects； yet when
applied to an object given by pure practical reason they enable us
to conceive the supersensible definitely； only so far； however； as
it is defined by such predicates as are necessarily connected with the
pure practical purpose given a priori and with its possibility。 The
speculative restriction of pure reason and its practical extension
bring it into that relation of equality in which reason in general can
be employed suitably to its end； and this example proves better than
any other that the path to wisdom； if it is to be made sure and not to
be impassable or misleading； must with us men inevitably pass
through science； but it is not till this is plete that we can be
convinced that it leads to this goal。
VIII。 Of Belief from a Requirement of Pure Reason。
A want or requirement of pure reason in its speculative use leads
only to a hypothesis； that of pure practical reason to a postulate；
for in the former case I ascend from the result as high as I please in
the series of causes； not in order to give objective reality to the
result （e。g。； the causal connection of things and changes in the
world）； but in order thoroughly to satisfy my inquiring reason in
respect of it。 Thus I see before me order and design in nature； and
need not resort to speculation to assure myself of their reality；
but to explain them I have to presuppose a Deity as their cause； and
then since the inference from an effect to a definite cause is
always uncertain and doubtful； especially to a cause so precise and so
perfectly defined as we have to conceive in God； hence the highest
degree of certainty to which this pre…supposition can be brought is
that it is the most rational opinion for us men。* On the other hand； a
requirement of pure practical reason is based on a duty； that of
making something （the summum bonum） the object of my will so as to
promote it with all my powers； in which case I must suppose its
possibility and； consequently； also the conditions necessary
thereto； namely； God； freedom； and immortality； since I cannot prove
these by my speculative reason； although neither can I refute them。
This duty is founded on something that is indeed quite independent
of these suppositions and is of itself apodeictically certain； namely；
the moral law； and so far it needs no further support by theoretical
views as to the inner constitution of things； the secret final aim
of the order of the world； or a presiding ruler thereof； in order to
bind me in the most perfect manner to act in unconditional
conformity to the law。 But the subjective effect of this law；
namely； the mental disposition conformed to it and made necessary by
it； to promote the practically possible summum bonum； this
pre…supposes at least that the latter is possible； for it would be
practically impossible to strive after the object of a conception
which at bottom was empty and had no object。 Now the above…mentioned
postulates concern only the physical or metaphysical conditions of the
possibility of the summum bonum； in a word； those which lie in the
nature of things； not； however； for the sake of an arbitrary
speculative purpose； but of a practically necessary end of a pure
rational will； which in this case does not choose； but obeys an
inexorable mand of reason； the foundation of which is objective； in
the constitution of things as they must be universally judged by
pure reason； and is not based on inclination； for we are in nowise
justified in assuming； on account of what we wish on merely subjective
grounds； that the means thereto are possible or that its object is
real。 This； then； is an absolutely necessary requirement；