246 / 298
Horst Steinke
246
Golden Century
, Dordrecht-Boston-London, D. Reidel Publishing, 1981, p.
100). The lens-making process is described in Gullan-Whur,
Within Reason
,
cit., p. 89. The tragedy was that the prolonged exposure to glass-dust exacer-
bated his chronic lung condition, and contributed to his early death (
ibid.
, p.
113).
500
For further background on the pivotal scientific role of optical instru-
ments in Spinoza’s age, see E. G. Ruestow,
The Microscope in the Dutch Republic:
The Shaping of Discovery
, Cambridge-New York, Cambridge University Press,
1996; on the development of optics theory, see F. J. Dijksterhuis,
Lenses and
Waves: Christiaan Huygens and the Mathematical Science of Optics in the Seventeenth
Century
, Dordrecht-Boston-London, Kluwer Academic, 2004.
501
For a discussion of details of Spinoza’s scientific views, see A. Gabbey,
Spinoza’s natural science and methodology
, in
The Cambridge Companion to Spinoza
,
cit., pp. 140-191; on optics, pp. 150, 153-155; on physics/kinematics, pp. 155-
169; on chemistry, pp. 178-180.
502
We are foregoing an examination of his treatment of optics, for which
Letters 39
and
40
could serve as case study; for example, whether Spinoza’s
treatment of spherical lenses lends itself to be seen through the “lens” of his
reflections on the circle and its associated infinities in
Ethics
, Part II, Proposi-
tion VIII, Note.
503
Spinoza took this example from his
Principles of Cartesian Philosophy
, Part
2, Propositions 9-11, for which see
Spinoza: Complete Works
, cit.
504
For a more detailed discussion of this illustration, see H. Boehme,
Analysis bei Hegel
, in «Mathematische Semesterberichte», 61, 2014, 2, pp. 159-
181, pp. 163-166.
505
With «Substance», Spinoza places the discussion explicitly at the heart
of his deepest philosophical reflections, and, furthermore, in the letter itself,
insists on its implications for the understanding of «the infinite»: «[…] Sub-
stance is not manifold, rather there exists only one Substance of the same na-
ture. […] no Substance can be conceived as other than infinite».
506
In Peterman’s view, «[…] there is good reason to think that these pas-
sages contain […] a deeper critique of the grounds of mechanism, on the basis
that the fundamental properties it posits satisfy the imagination but not the
intellect. […] So is appears that Spinoza would hold physicists to his highest
standard of knowledge» (Id.,
Spinoza on Physical Science
, cit., pp. 216-217).
507
He argues that «[o]ur conclusion is reached because number is not ap-
plicable to the nature of the space between two non-concentric circles».
508
In the letter, Spinoza not only dealt with the subject as such, but also
included references to those who did not share his philosophy, such as: «if
men had paid careful attention to these distinctions», «all who have attempted