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Shizuki, Tadao


(b. Nagasaki, Japan, 1760; dd. Nagasaki, 22 August 1806)

natural philosophy.

Tadao’s surname by birth was Nakano, but he was adopted by the Shizuki family, whose head was a government interpreter from the Dutch. His nickname was Tadajiro, and professionally he was known as Ryuho. In 1776 he became an assistant interpreter, succeeding his adoptive father, but he retired from that post the following year because of ill health. After leaving public service, he spent the rest of his life in the private study of Dutch books and in contemplation. Although his health was delicate and he had a reputation for unsociability, he attracted brilliant followers. He wrote books about the Dutch langiage and partially translated the Dutch translation of Engerbert Kaempher’s Geschichte und Beschreibug von Japan. But Tadao’s major work was Rekisho shinsho, a compilation of his own theories on natural philosophy, inspired by his translation of the Dutch version of John Keill’s Introductio ad physicam and the Introductio ad veram astronomiam.

Tadao’s natural philosophy was unusual within the Japanese intellectual tradtion. His appraoch to problems was close to that of modern Western natural philosophers: he attempted to find fundmental explanations fro all natural phenomena rather than merely describe them as moral, aesthetic, or practical problems.

Western mechanistic philosophy must have seemed remote and uninteresting in an intellectual climate dominated by Confucius’ moral supreme doctrine, but Tadao nonetheless absorbed himself for twenty years in translating Keill’s book and constructing his own natural philosophy. Perhaps he was able of to do so because he was removed from the intellectual tradition centered around the Japanese Confucains and because he was able to pursue his study in Nagasaki, which was then the only opening to the outside world. Japanese knowledge of western science was at that time very limited. While Chinese translations of Western books on science had just been released from governmental ban, these were the work of Jesuits stationed in China and covered only Tychonic astronomy. The only sources for Copernicansim and Newtonianism were books brought in by the Dutch, who were the only Westerners permitted to trade with Japan and who were permitted to land only at Nagaski. Todao was thus ideally situated.

Other interpreter and physicians had contributed to introducing modern Western science into Japan, but Tadao had a far better understanding of the Dutch language and a superior insight into philosophical concepts. It is therefore curious that he chose to spend so much of his life translating Keill’s book. If he meant simply to introduce Western natural science, why did he not choose other popular, up-to-date books and well-arranged texts, such as, for example, Benjamin Martin’s philosophical Grammar, the Dutch translation of which must have been easy to obtain despite the limited availability of Dutch books?

Although he translated other works on request, Tadao probably concentrated on Keill’s book because it was difficult, under the import restrictions, to find an equally sophisticated work and because the other textbooks and popular books available to him did not give him the same intellectual satisfaction. In advocating Newtonianism, Keill’s work had a polemical tone, and more importantly and quite unlike the readjusted interpretations of later authors, it dealt in abstractions and included a great many elements of natural philosophy. The book especially suited Tadao’s inclination toward natural philosophy and Tadao thus became the first Newtonian in the East.

The earliest extant manuscript of Tadao’s translation ofKeill’s worjk is “On Attractive Force” (1784). Considering the level of knowledge of Western science in the Orient at that time, it would seem that Tadao struggled excellently with a very difficult subject. Since Copernican theory can be grasped as conceptional difficulty to the Oriental mind; but Newtonianism was being introduced into the Orient for the first time, and there was no Japanese vocabulary to embrace the concepts of corpuscle, vacuum, gravity, or force, Tadao therefore had to invent such words, and some of his inventions became standard in countries in which Chinese characters are used. The concept of atomism was also unknown in the Orient, and Tadao attempted to adopt the neo-Confucian idea of ch’i as a corresponding notion; but since the concept of ch’i is based on the model o a continuoulsy changing fluid, he found it difficult to combine the idea of discrete atoms with the monistic ch’i concept of condensation and rarefaction.

Atomism requires a clear distinction between atom and vacuum, but for Tadao vacuum was a rarefied state of ch’i; and atom and vacuum were continuously caught in the spectrum of rarefaction of ch’i. Keill, however, explained electrical phenomena by means of effluvia, and Tadao found the concept of effluvia much more congenial to interpretation by ch’i that of the atom. Tadao also claimed that effluvia offered an explanation for not only electrical force but also gravity. Since he considered weight to be the accumulation of ch’i, both electromagnitic force and gravity could be explained thereby.

Tadao’s commentary contains many original ideas. He applied Western principles of attractive force and the traditional idea of Yin-Yang to the explanation of the phenomenal world. His adaptation of Yin-Yang incorporated two different— positive and negative– forces, and he used the variation in the balance of these two forces to explain what Western scientists considered to be a variation in the magnitude of only one force. Had Tadao developed this idea further he might have constructed his own system, which would probably have been significantly different from its Western counterpart. His method seems particularly suitable to the explanation of electromagnetic force.

Although Tadao and Keill were from completely different academic environments, Tadao’s native aptitude seems superior to Keill’s, and he himself even experimented with a barometer, at a time when a Japanese experimental science barely existed. The subjects that Tadao tried to explain by attractive force—other than the data he obtained from Duct book—were, however, limited to spontaneously occurring phenomena—as, for example atmospheric events and plant life. (He even tried to construct a primitive vegetable physiology based upon attractive force.).

In his work on attractive force Keill developed the ideas of Newton’s Opticks and tried to explain chemical and other phenomena by means of homogeneous particles and their intermolecular force, using the inverse third or fourth powers of their distances. But he could neither measure nor test what he wanted to prove and thus failed to achieve his objective. Unlike Keill and other Newtonians who sought to prove quantitative change in chemical phenomena, Tadao lacked the social background that might have fostered an interest in chemistry; and no such academic discipline had yet developed in Japan. Thus his interest in attractive force remained purely that of a natural philosopher.

The theory of cosmic dual forces in Tadao’s commentary “On Attractive Force” is compatible with modern science, and there is the possibility that one subsumes the other: it is an acceptable and permissible concept for modern scientists. But in his later studies Tadao’s ideas conformed more closely to traditional natural philosophy, and they became more speculative. During this time he completed hisRekisho shinsho, in which he commented systematically on Newtonian dynamics—although he was concerned primarily with their metaphysical basis: “All things have the property of gravity. Although gravity originally emerged from the inexplicable process of creation, it can be comprehended by the intelligence and hence is not absolutely inexplicable. Yet the cause of gravity is quite inscrutable. Even with advanced Western instruments and mathematics, the fundamental cause is indeterminable.”

Although the second volume of Rekisho shinsho was entitled Immeasurable, Tado sought in Oriental thinking a solution for matters that in the West would have been explained as acts of God. He established unitary ch’i and its dual function (rarefaction and condensation) as the basis for his natural philosophy and thus wrote that

The space of the universe contains only one substance. chi but it can also be either empty or full. Thus in one there is two, and in two, one. If there were only the one, there could be no difference between the rarefied and the condensed. Is there not then a difference between the rarefied and the condensed? By the existence of these two contrary principles the phenomena are caused in endless succession. Because of the oneness of the substance, the universe is monistic. The cause of these principles is beyond may comprehension, but the best way to comprehend the subtlety of these principles is to study the teaching of the Book of Changes [I-Ching]

If there were only the two, the ch’i of heaven and earth could not be transmitted from one to the other. The shining ch’i of the sun and heavenly bodies is reflected form one to the other, and goes to and from the extremities of heaven. Permeating space without a single gap, it rises and falls, undergoing countless transformations. We must, then, admit that there is only a single ch’i. …which differs in respect to condensation and rarefaction are the same in causal origin as emptiness and plenitude. The extreme of rarefaction is emptiness. Perfect plenitude and perfect emptiness, combining with each other, make a single state. This is why Laotzu said, “Nonexistence occupies nonspace.” Nevertheless, even in the extremities of heaven, there is not the slightest space of pure plenitude or nonemptiness.

We must acknowledge that the light of the stars can permeate the broad heavens, and that the ch’i of fire can penetrate rock and metal. For example although winter is cold, and summer hot, even in winter there is still some warm ch’i. and even in summer there is some cold ch’i. Or take the case of soil, placed in water. As the soil is condensed and heavy, the water, being light and rarefied, is like heaven. The soil, mixing with the water, discolors it; and the water, permeating the soil, moistens it. Therefore in the water there is nowhere where the soil ch’i is absent, and in the soil, nowhere where the water ch’i is absent.

Accordingly, Tadao arranged the subjects of Newtonina dynamics, including gravity, into a series of chapters on divination, theory of monistic ch’i, and Newtonian dynamics. He was not as successful, however, in relating the natural philosophy that he derived from the theory of monistic ch’i to Newtonian dynamics.

Tadao was one of the first to introduce Copernican theory into the Orient, although his interest was not in heliocentric theory. The locational relationship between the sun and the universe was for him simply a problem of changing the coordinate system: and, from the natural-philosophical point of view, it was not a substantial problem. In traditional neo-Confucian cosmology the problem in in volved the dynamics of motion and inactivity. Tadao did not refer to Copernicanism as a heliocentric theory but, rather, as an earth-moving theory, in which heaven and earth are composed of the cosmic dual forces of ch’i. The fast and light ch’i ascend and become heaven while the heavy and slow ch’i gather together and become earth. This system represents Chu Hsi’s dynamic cosmogony and, unlike Aristotelian celestial-terrestrial dichotomy, makes no sharp distinction between heaven and earth, motion and inactivity. Another neo-Confucian philosopher also thought that the earth did not have absolute fixation in the middle of the universe but was situated at one end of a continuous spectrum binding Yin-Yang polar concepts (for example, shade and light, inactivity and motion, slow and fast) and that it rotated in relation to its surroundings.

Tadao viewed Copernicanism as absolute relativism but could not decide whether earthly or heavenly motion was more correct. He also pointed out that he had found the word “earth moving” in an ancient Chinese book and went on to suggest that the Chinese first conceived the earth-moving theory. (The word “earth moving” as it appears in this ancient text can also be translated as “earthquake,” however.) The term “earth moving,” as Tadao used it, has been retained as a scientific, technical word, even though it does not distinguish rotation from revolution.

Tadao also raised the question of why the planets rotate and revolve in the same direction in planes not greatly inclined to the ecliptic. In a section entitled “Kenkon bunpan zusetsu” (“The Formulation of the Cosmos, Illustrated”) he proposed a hypothesis concerning the formation of the planetary system. His hypothesis recalls immediately the celebrated hypothesis of Kant and Laplace. Because of the relative inaccessibility of Western treatises, however, it is unlikely that Tadao derived his idea from anyone else. In view of his background in neo-Confucian ideas, his hypothesis was not a titanic leap—many aspects of it were already present in neo-Confucian vortex cosmogony. Hence, an infusion of ideas concerning attraction and centrifugal force provided Tadao with a more elaborate mecahnical hypothesis, which he formulated in accordance with the heliocentric system.


Tadao’s major works are Rekisho Shinsho (“New Treatise on Calendrical Phenomena”; Heibon-sha, 1956), 2 vols., Japanese Philosophical Thoughts no. 9; and Kyurikiron (“On Attractive Force”; Iwanami, 1972).

On Tadao and his work in Western languages, see Yoshio Mikami, “On Shizuki Tadao’s Translation of Keill’s Astronomical Treatise,” in Nieuw archief voor wiskunde, 11 (1913), 1–11; Shigeru Nakayama, History of Japanese Astronomy (Cambridge, Mass., 1969); Ohmori Minoru, “A Study of the Rekisho Shinsho,” in Japanese Studies in the History of Science, no. 2 (1963), 146–153, and no. 3 (1964), 81–88; S. Yajima, “Théorie nébulaire de Shizuki (1760–1806),” in Archives internationals d’historie des sciences, 12 (1956), 169–173; and Tadashi Yoshida, “The Rangako of Shizuki Tadao; the Introduction of Western Science in Tokugawa Japan,” Ph.D. thesis at Princeton University (1974).

In Japanese are Kanda Shigeru, “Translations by Shizuki Tadao,” in Rangaku shiryo Kenkyukai Hokoka, no. 107 (1961); Hiroto Saigusa, “On Newton, Who Existed in Japan the Past Two Centuries,” in Yokohama Daigaku Ronso, Social Science, no. 1 (1958); Watanabe Kurasuke, “Summary on Work of Dutch Translator, Shizuki,” in Nagasaki Gakkai Sosho, 4th ed. (1957).

Shigeru Nakayama

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