son or by
scientific thinking, but primarily through the will, or as Kant prefers
to call it, the practical reason. What is meant by the practical reason
is the intelligence, the will and the affections operating together;
that is to say, the whole man and not merely his intellect, directed to
those problems upon which, in sympathy and moral reaction, the whole man
must be directed and upon which the pure reason, the mere faculty of
ratiocination, does not adequately operate. In the practical reason the
will is the central thing. The will is that faculty of man to which
moral magnitudes appeal. It is with moral magnitudes that the will is
primarily concerned. The pure reason may operate without the will and
the affections. The will, as a source of knowledge, never works without
the intelligence and the affections. But it is the will which alone
judges according to the predicates good and evil. The pure reason judges
according to the predicates true and false. It is the practical reason
which ventures the credence that moral worth is the supreme worth in
life. It then confirms this ventured credence in a manifold experience
that yields a certainty with which no certainty of objects given in the
senses is for a moment to be compared. We know that which we have
believed. We know it as well as that two and two make four. Still we do
not know it in the same way. Nor can we bring knowledge of it to others
save through an act of freedom on their part, which is parallel to the
original act of freedom on our own part.

How can these two modes of thought stand related the one to the other?
Kant's answer is that they correspond to the distinction between two
worlds, the world of sense and the transcendental or supersensible
world. The pure and the practical reason are the faculties of man for
dealing with these two worlds respectively, the phenomenal and the
noumenal. The world which is the object of scientific investigation is
not the actuality itself. This is true in spite of the fact that to the
common man the material and sensible is always, as he would say, the
real. On the contrary, in Kant's opinion the material world is only the
presentation to our senses of something deeper, of which our senses are
no judge. The reality lies behind this sensible presentation and
appearance. The world of religious belief is the world of this
transcendent reality. The spirit of man, which is not pure reason only,
but moral will as well, rec