Silent Years 195form of inner sense was "the most essential" that could be made to his
system, and that it "occasioned considerable reflection on his part."^25
At this time, there had already been other responses. Sulzer, in a letter
of December 8, 1770, found Kant's theory "not just thorough but impor¬
tant." He had one small problem: until now he had been convinced that
Leibniz's view of space and time was correct, that the concepts of "space"
and "time" differed from those of "duration" and "extension." The latter
pair consisted of simple concepts, the former of complex concepts that
could not be thought without the concept of order. He agreed with Kant on
the "natural influx of substances," and had thought of it as Kant did for a
long time. He also had ideas about the difference between the sensible and
the intelligible, and he was looking forward to hearing more.^26 There were
also criticisms. Mendelssohn had written to Kant on December 25, 1770:Your dissertation has now reached my eager hands, and I have read it with much pleas¬
ure. Unfortunately my nervous infirmities make it impossible for me of late to give as
much effort of thought to a speculative work of this stature as it deserves. One can see
that this little book is the fruit of long meditation, and that it must be viewed as part
of a whole system.... The ostensible obscurity of certain passages is a clue... that
this work must be part of a larger whole... since you possess a great talent for writ¬
ing in such a way as to reach many readers, one hopes that you will not always
restrict yourself to the few adepts who are up on the latest things, and who are able to
guess what lies undisclosed behind the published hints.
Since I do not count myself as one of these adepts, I dare not tell you all the thoughts
that your dissertation aroused in me. Allow me only to set forward a few, which do not
concern your major theses but only some peripheral matters.^27
A nice put-down; Mendelssohn criticized Kant, who had just received a
professorship because he was such a popular teacher and writer, for being
obscure. After pointing out that he himself had said something on infinite
extension that was very close to what Kant put forward in the dissertation
(and that he would send him the second edition of his Philosophical Writ¬
ings), he criticized him for identifying Shaftesbury's moral instinct with
the Epicurean feeling of pleasure. His most important criticism concerned
Kant's conception of time. Kant had claimed in the dissertation that we
know what the word "after" means only because of an antecedently formed
concept of time.^28 Mendelssohn found that the word "after" may indeed
have at first only chronological meaning, but that it is possible to use it
for any order in general "where A is possible only when or in case B does
not exist. In short, it can mean the order in which two absolutely (or even