§ 16. After this full consideration of reason as a special faculty of
knowledge belonging to man alone, and the results and phenomena peculiar
to human nature brought about by it, it still remains for me to speak of
reason, so far as it is the guide of human action, and in this respect may
be called _practical_. But what there is to say upon this point has found
its place elsewhere in the appendix to this work, where I controvert the
existence of the so-called practical reason of Kant, which he (certainly
very conveniently) explained as the immediate source of virtue, and as the
seat of an absolute (_i.e._, fallen from heaven) imperative. The detailed
and thorough refutation of this Kantian principle of morality I have given
later in the “Fundamental Problems of Ethics.” There remains, therefore,
but little for me to say here about the actual influence of reason, in the
true sense of the word, upon action. At the commencement of our treatment
of reason we remarked, in general terms, how much the action and behaviour
of men differs from that of brutes, and that this difference is to be
regarded as entirely due to the presence of abstract concepts in
consciousness. The influence of these upon our whole existence is so
penetrating and significant that, on account of them, we are related to
the lower animals very much as those animals that see are related to those
that have no eyes (certain larvae, worms, and zoophytes). Animals without
eyes know only by touch what is immediately present to them in space, what
comes into contact with them; those which see, on the contrary, know a
wide circle of near and distant objects. In the same way the absence of
reason confines the lower animals to the ideas of perception, _i.e._, the
real objects which are immediately present to them in time; we, on the
contrary, on account of knowledge in the abstract, comprehend not only the
narrow actual present, but also the whole past and future, and the wide
sphere of the possible; we view life freely on all its sides, and go far
beyond the present and the actual. Thus what the eye is in space and for
sensuous knowledge, reason is, to a certain extent, in time and for inner
knowledge. But as the visibility of objects has its worth and meaning only
in the fact that it informs us of their tangibility, so the whole worth of
abstract knowledge always consists in its relation to what is perceived.
Therefore men naturally attach far more worth to immediate and perceived
knowledge than to abstract concepts, to that which is merely thought; they
place empirical knowledge before logical. But this is not the opinion of
men who live more in words than in deeds, who have seen more on paper and
in books than in actual life, and who in their greatest degeneracy become
pedants and lovers of the mere letter. Thus only is it conceivable that
Leibnitz and Wolf and all their successors could go so far astray as to
explain knowledge of perception, after the example of Duns Scotus, as