Routledge History of Philosophy Volume IV

SPINOZA: METAPHYSICS AND KNOWLEDGE 257
of these—Ep 36, 39, 40, 46—should deal with problems of optics, and more
specifically with problems concerning lenses, is not surprising; it is well known
that Spinoza, after his expulsion from the synagogue, supported himself by
grinding and polishing lenses. But other letters display an interest in science that
is not purely professional. Spinoza corresponds with Robert Boyle about nitre,
fluidity and firmness (Ep 6, 11, 13, 16); he discusses with the secretary of the
Royal Society, Henry Oldenburg, recent work on comets (Ep 29–32) and
Descartes’s theories about the planets (Ep 26); he comments on Descartes’s laws
of motion and Huygens’s criticism of these, and asks for news of an experiment
carried out in the Royal Society to test a hypothesis of Huygens (Ep 32, 33); he
discusses the calculation of chances (Ep 38) and reports on an experiment of his
own about pressure (Ep 41). This interest in the sciences is confirmed by a list of
books from his library that were put up for sale after his death. 21 Of the 161
books listed, roughly a quarter are mathematical or scientific works. 22
To sum up, my aim has been to determine the intellectual context within
which Spinoza’s thought is to be placed. I have argued that there is no reason to
believe that Spinoza was deeply imbued with the Jewish or Christian philosophy
of the Middle Ages. He may occasionally quote the medievals in order to make a
point, but they are not the well-spring of his philosophy. His interest is not in old
philosophical ideas, but in modern ones, in particular the philosophy of
Descartes, which he ‘reforms’, and the new science of his time.
I have spoken of Spinoza’s interest in contemporary science; before going
further into his philosophy, something must be said in general terms about the
way in which he saw the relations between science and his philosophy. It is a
commonplace that, whereas Descartes was chiefly concerned with the answer to
the question, ‘What do I know, and how do I know it?’, Spinoza is chiefly
concerned with the question, ‘What is a good life for a human being?’ It may be
that had Spinoza lived longer the Ethics would not have had the dominant
position in his output that it now has; it might have been accompanied, not only
by a completed Tractatus Politicus, but by a revised and completed version of
his treatise on method, a book on physics, and an introduction to algebra. 23
Notwithstanding all this, there is no doubt that Spinoza’s initial and chief motive
for philosophizing was a moral one. In the famous autobiographical opening of his
Tractatus de Intellectus Emendatione, he writes: 24
After experience had taught me that all the things which occur frequently
in ordinary life are vain and futile; when I saw that all the things on account
of which I was afraid, and which I feared, had nothing of good or bad in
them except in so far as the mind was moved by them, I resolved at last to
inquire if there was some good which was genuine and capable of
communicating itself, and by which the mind would be affected even if all
the others were rejected.