Founder of a Metaphysics of Morals 309the debate on important questions too early, Kant uses a passage of the
Morning Hours in which Mendelssohn said: "When I tell you what a thing
causes or suffers, then do not ask the further question 'What is the thing?'
When I tell you what concept you must form of a thing, then the other
question 'What is the thing in itself?' does not make any sense." Referring
to his own theory as developed in the Metaphysical Foundations of Nature,
Kant points out that we can only know space, things in space, the spatiality
of these things, and motions, that is, external relations. Could someone like
Mendelssohn really say that this is the same as knowing the thing in itself?
The answer, Kant claims, can only be no. Therefore the question makes
sense. We can ask "what this thing in itself is, which in all these relations
is the subject."
To be sure,
If we knew the effects of a thing which really could be qualities {Eigenschaften) of a thing
in itself, then we would no longer be permitted to ask what the thing in itself is apart
from these qualities, for it is then just what is given by these qualities.^148
Kant then goes on to say that he will probably now be asked (by Mendels-
sohnians) to give examples of such qualities that "would permit one to dif¬
ferentiate them and by means of them things in themselves." He answers:
this has long been done - and it was you who did it. Just look at how you obtain the
concept of God as the highest intelligence. You think in it only true reality, that is,
something that is not just the opposite of negations ... but also and primarily opposed
to the realities in the appearance {realitas phaenomenon), like all the realities which are
given to us by the senses and which are therefore called realitas apparens.... Now, if
you diminish all these realities (understanding, will, godliness, power, etc.) by degrees,
they still remain always the same as far as their quality is concerned. Thus you get the
qualities of the things in themselves, which you can also apply to other things, differ¬
ent from God.^149
Noting that it is "peculiar" that we can determine our concepts of things
in themselves only by first reducing all reality to God, and only then apply¬
ing it to things themselves, he claims that this is the only way to separate
(Scheidungsmittel) what is sensible appearance from what can be consid¬
ered by the understanding as a thing in itself. It pays to pursue questions
as far as possible — or so Kant thought.
During this time Kant also worked on his review of Gottlieb Hufeland's
Essay on the Basic Principle of Natural Law (Leipzig, 1785).^150 It appeared
in the, Allgemeine Literatur-Zeitung of April 1786. Kant had been sent the
book by the author in October 1785, and then been asked by the editor