Distinguished Sir, --With regard to your question as to
whether the variety of the universe can be deduced a
priori from the conception of extension only, I believe I have
shown clearly enough already that it cannot; and that,
therefore, matter has been ill-defined by Descartes as extension;
it must necessarily be explained through an
expresses eternal and
essence. But perhaps, some day, if
my life be prolonged, I may discuss the subject with you more
clearly. For hitherto I have not been able to put any of these
matters into due order.
As to what you add; namely, that from the definition
of a given thing considered in itself we can only deduce single
property, this is, perhaps, true in the case of very simple things
(among which I count figures), but not in realities. For, from
the fact alone, that I define
God as a Being to whose
I infer several of His properties; namely, that
He necessarily exists, that He is One, unchangeable,
&c. I could adduce several other examples, which, for
the present, I pass over.
In conclusion, I ask you to inquire, whether Huet's treatise
(against the "Tractatus Theologico-Politicus") about which I
wrote to you before, has yet been published, and whether you
could send me a copy. Also, whether you yet know, what
are the new discoveries about refraction. And so farewell, dear
Sir, and continue to regard yours, &c.
The Hague, 15 July, 1676.