Following completion of the Tenpo calendar, Kagesuke wrote a book, Shinpo
Rekisho (新法暦書, Calendrical Treatise by the New Method), in 1846. In its
preface, Kagesuke criticized the concept of heliocentrism. He emphasized that the
difference between geostatic motion and heliocentric motion of planets was merely a
matter of coordinate transformation; the astronomical implication is all the same for
the purpose of calendar making. Both theories have an equal logical claim to
verisimilitude. Kagesuke’s attitude reflected a traditional astronomer’s approach,
not open to new cosmological and physical concepts. Astronomers in his period
remained tradition-bound within the framework of calendar reform and accepted
Western astronomy in its technical aspects, but not in its cosmology.
1.3 Acceptance of Western Cosmology
In the Tokugawa period, Western knowledge in science and technology was transmitted via the Dutch language. Astronomy, mapmaking, calendar making, and
medicine are among the main fields whose knowledge was acquired from Dutch
texts. Dutch interpreters in Nagasaki were officers of the Edo government and
promoted trade and cultural exchange. Dutch learning gradually spread among
scholars in Edo and Osaka.
Gradually, Western cosmologies, Aristotelian, Copernican, and Newtonian, were
introduced and successively accepted (Hirose 1964; Nakayama 1969).
1.3.1 Mukai Gensho and Aristotelian Cosmology
Mukai Gensho (向井玄升, 1607–1677) introduced Western astronomical ideas in
Japan during the early Tokugawa period (Hockey et al. 2007; Nakayama 1969).
He was born in Hizen (肥前, now Saga Prefecture, Kyushu) and moved to
Nagasaki, where he learned Confucian philosophy and medicine, as well as astronomy. In 1658, he moved to Kyoto, where he practiced medicine and remained until
his death. Mukai was interested in Western astronomy based on Aristotelian cosmology and wrote a set of commentaries around 1650, entitled Kenkon Bensetsu (乾
坤辯説, Western Cosmography, with critical commentaries). This book was written
based on a translation by the apostate Jesuit missionary Christoph Ferreira (Japanese
name, Sawano chu’an 沢野忠庵).
In Kenkon Bensetsu he introduced the geocentric Aristotelian system to Japan
with some commentary. In this system, heaven consists of nine spherical shells
surrounding the spherical earth at rest. The Sun, Moon, and planets are fixed in their
respective shells, and fixed stars are placed on one shell. Heavenly bodies are made
of perfect matter, composed of four elements: earth, water, fire, and wind.
Mukai made two comments in Kenkon Bensetsu. One was his opposition to the
four-element hypothesis. He argued that terrestrial materials are composed of five
6
1 Astronomy in the Tokugawa Period, 1603–1868
Rekisho (新法暦書, Calendrical Treatise by the New Method), in 1846. In its
preface, Kagesuke criticized the concept of heliocentrism. He emphasized that the
difference between geostatic motion and heliocentric motion of planets was merely a
matter of coordinate transformation; the astronomical implication is all the same for
the purpose of calendar making. Both theories have an equal logical claim to
verisimilitude. Kagesuke’s attitude reflected a traditional astronomer’s approach,
not open to new cosmological and physical concepts. Astronomers in his period
remained tradition-bound within the framework of calendar reform and accepted
Western astronomy in its technical aspects, but not in its cosmology.
1.3 Acceptance of Western Cosmology
In the Tokugawa period, Western knowledge in science and technology was transmitted via the Dutch language. Astronomy, mapmaking, calendar making, and
medicine are among the main fields whose knowledge was acquired from Dutch
texts. Dutch interpreters in Nagasaki were officers of the Edo government and
promoted trade and cultural exchange. Dutch learning gradually spread among
scholars in Edo and Osaka.
Gradually, Western cosmologies, Aristotelian, Copernican, and Newtonian, were
introduced and successively accepted (Hirose 1964; Nakayama 1969).
1.3.1 Mukai Gensho and Aristotelian Cosmology
Mukai Gensho (向井玄升, 1607–1677) introduced Western astronomical ideas in
Japan during the early Tokugawa period (Hockey et al. 2007; Nakayama 1969).
He was born in Hizen (肥前, now Saga Prefecture, Kyushu) and moved to
Nagasaki, where he learned Confucian philosophy and medicine, as well as astronomy. In 1658, he moved to Kyoto, where he practiced medicine and remained until
his death. Mukai was interested in Western astronomy based on Aristotelian cosmology and wrote a set of commentaries around 1650, entitled Kenkon Bensetsu (乾
坤辯説, Western Cosmography, with critical commentaries). This book was written
based on a translation by the apostate Jesuit missionary Christoph Ferreira (Japanese
name, Sawano chu’an 沢野忠庵).
In Kenkon Bensetsu he introduced the geocentric Aristotelian system to Japan
with some commentary. In this system, heaven consists of nine spherical shells
surrounding the spherical earth at rest. The Sun, Moon, and planets are fixed in their
respective shells, and fixed stars are placed on one shell. Heavenly bodies are made
of perfect matter, composed of four elements: earth, water, fire, and wind.
Mukai made two comments in Kenkon Bensetsu. One was his opposition to the
four-element hypothesis. He argued that terrestrial materials are composed of five
6
1 Astronomy in the Tokugawa Period, 1603–1868