Fang Yizhi (1611-1671), a famous philosopher and scientist in the Ming Dynasty. His name is Mizhi, his pseudonym Mangong, and his name is Luqi, Longmianyuzhe, etc., a Han nationality, a native of Tongcheng, Anhui. He was a Jinshi in 13 years of Chongzhen and was an official reviewer. During the reign of Hongguang, he was slandered by Ma Shiying, Ruan Dacheng, and fled to Guangdong to sell medicine for self-support. During the Yongli period, he served as Zuo Zhongyun, and was falsely impeached. After the Qing army entered Guangdong, he became a monk in Wuzhou. His Dharma name was Hongzhi. He wrote hard and wrote secretly.

He secretly organized anti-Qing and restoring the Ming Dynasty. In March of the 10th year of the reign of Emperor Kangxi, he was arrested for the "Guangdong Difficulty". In October, he sank himself in Wan'an, Jiangxi for his death in the country. In the academic world, he learned from his wisdom and learned from others' strengths, and advocated the combination of Chinese and Western cultures, Confucianism, Buddhism and Taoism. He wrote more than 4 million words in his life, and most of them were lost. He had dozens of works in his life, with extensive content, including literature, history, philosophy, territorialism, medicine, physics, and everything.

Fang Yizhi has adhered to family education since childhood and received traditional Confucian education. He was raised by his mother and aunt since childhood. His aunt Fang Weiyi was the daughter of Fang Dazhen, Shaoqing of Dali, Ming Dynasty, and the wife of Yao Sunqi, and was widowed. Fang Weiyi was quite talented and was a famous female poet at that time. He once traveled with his father to Jiading, Sichuan, Funing, Hebei, Beijing and other places, and saw famous mountains and rivers, and lived in Jinghua, and read Western books. He had a lot of knowledge. In addition to family education, the teachers he taught were also works by the time.

Bai Yu, a famous scholar, is good at poetry, classics and history, and advocates practical learning. Wang Xuanze specializes in exegesis of famous things and the "He" and "Luo" and is rigorous in his studies. He is a master of the "Spring and Autumn Annals" at that time. Fu Haifeng was a famous doctor at that time. In addition, he had a rich collection of books in his family and was known as the Jigutang, which "both rooms are both in the sea of ​​words, and the beginning of Xihuang". In such an environment, Fang Yizhi in his youth was influenced by a strong academic atmosphere. Because his ancestors were directly or indirectly related to the Donglin Party.

Fang Yizhi loved natural science knowledge. After reading in school, he loved to be exhausted by physics. He once said, "I am not filial and wisdom, and I have the extreme essence of things." (Volume 5 of "Small Knowledge of Physics") During the Ming and Qing dynasties, Western learning spread to the east. Fang Yizhi adhered to family education while learning from the Book of Changes. On the other hand, he had extensive contact with missionaries to learn Western learning. After tireless efforts, he finally achieved great achievements in both philosophy and science, and reached a considerable height.

Fang Yizhi was very knowledgeable. The legend of "Draft History of Qing Dynasty": "With wisdom, he has different roots, and can recite the history of 15 groups of classics and zis in the age of 15 years. He has extensive knowledge and knowledge, from astronomy, geography, rituals, music, law, sound, words, calligraphy, painting, medicine, and skills, all of which can examine their origins and analyze their purpose." This evaluation is not excessive. He has his own unique insights in many fields. For example, in terms of academic classification, he divided academics into three categories, saying:

"The study of the family of heaven and earth, the numbers, rules and calendars, sounds, and medicine are all the principles of quality and physics. If you are dedicated to governing teachings, you will be responsible for reason. If you are dedicated to the number of things, you will be the ultimate principle of things." ("Tongya·Article and Torture")

Among these three academics, he talked more about the translation and quality test. He said:

"The aggregate of silence and feeling deeply explores the origin of it, which is called the main point; because things have their own reasons, they are actually investigated. It is large and the original meaning is small and the plants are stupid and creeping, which is similar to their nature, conjuring their likes and dislikes, and optimizing their constant changes. This is called quality measurement." ("Small Physics·Preface")

It can be seen that the so-called "Tongji" is a discussion of the fundamental reasons for things, while quality measurement requires down-to-earth investigation of the causes of changes in things, sorting and classification according to characteristics, summarizing and verifying known laws, and predicting future development and changes. Obviously, "Tongji" and "Qiji" are classifications made from research purposes and research methods. In China, this classification is the original creation of Fang Yizhi.

In astronomy, Fang Yizhi combined traditional Chinese astronomy with Western astronomy introduced by missionaries at that time to discuss the theory of geocentricity, the Nine Heavens Theory, the Yellow Equator, the Age of the Year, the Stars,

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Astronomical issues such as solar and lunar eclipses, calendars, etc. He attaches great importance to Western astronomy knowledge and often tracks the latest progress in Western astronomy. For example, when he discussed the orbit of celestial bodies, he once proposed the correct guess that Venus and Mercury orbits the sun based on the fact that the West used a telescope to observe the sky and found that Venus had phases changed.

Fang Yizhi accepted Western scientific knowledge, not blindly following, but through his own careful thinking and digestion. For example, he first examined the observational evidence on which the earthly circle theory relied, and then accepted it. He refuted the wrong statements of the missionary. For example, the missionary once said that the radius of the sun is more than 160 times the radius of the earth, and the sun is only more than 16 million miles away from the earth. Fang Yizhi pointed out that this is wrong, because based on this calculation (it is determined that the circumference of the earth is about 90,000 miles), the diameter of the sun is nearly one-third of the distance between the sun and the earth, which is obviously impossible. He used his "light, fat, shadow, and thin" theory to explain this problem, pointing out that the sun's circle surface seen by human eyes is larger than the actual luminous body, so the measurements made by geometric methods are not accurate. His theory was later accepted by the author of "Li Xiang Ke Cheng".

In physics, Fang Yizhi has many more creative ideas. He proposed a simple theory of light fluctuation based on the monistic view of qi, believing that: "Qi condenses into shape and emits light sound, and there is still air that has not condensed shape and sucks with it. Therefore, the use of shape stops at its division, while the use of light sound often overflows the rest: qi has no gaps, and it is mutually resonant." (Volume 1 of "Small Knowledge of Physics")

Obviously, Fang Yizhi believes that the generation of light is due to the excitation of qi. Since qi spreads in all spaces and has no gaps between them, the excited qi must interact with the surrounding static qi, "sucking and sucking" to transmit the excitation, which forms the propagation of light. Therefore, what Fang Yizhi described is a simple theory of light fluctuation. In order to distinguish it from the electromagnetic fluctuation theory of modern light, it can be called the qi-light fluctuation theory.

From the perspective of the theory of qi and light fluctuation, Fang Yizhi further proposed the idea that light does not go straight, which he called it light fat, shadow thin, and believed that

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During the propagation process, light always invades into the shadow range of geometric optics, so that the lighted area is expanded and the shadowed area is reduced. He also pointed out that due to the existence of light weight and thinness, the results obtained by measurements based on the direct progression of light are inaccurate. He said:

"The object is obstructed by the shape, and its shadow is easy to end. Sound and light often overflow the number of objects. Sound cannot be seen, light can be seen, but measurement cannot be accurate." (Volume 1 of "Small Knowledge of Physics")

In order to confirm his point of view, he also conducted small hole imaging experiments and tried to use his own theory to explain common optical phenomena. All of these are very new in the history of the development of physics.

In addition, his descriptions of the reflection and refraction of light, the occurrence, propagation, reflection, sound insulation effect of sound, dispersion, coking, specific gravity, magnetic effect, etc. are ahead of his contemporaries.

In biomedical science, Fang Yizhi also has many points worth mentioning. In his book "Small Physics", he recorded a large number of ecological contents and knowledge of animals and plants, cultivation, management, etc. He quoted the missionaries' "brain master thinking", introduced their knowledge about human skeletons, muscles, etc., and believed that Chinese and Western studies have their own strengths. He once said that Western medicine "detailed in quality measurements, but not in words and a few words". Therefore, he quoted Tang Ruowang's "Main-Corporate Constitution" anatomy of traditional Chinese and Western medicine, and introduced it to the Chinese people, but eliminated the contents of "the almighty God created the world" mentioned by the missionaries. He himself has a long research on traditional medicine and has written a variety of medical works. Unfortunately, these works are not passed down from generation to generation, and it is difficult for us to get a glimpse of the whole picture. Fang Yizhi is regarded as one of the early Huitong thought doctors in my country, and has a certain influence on the history of the development of modern medicine in my country.

Fang Yizhi wrote many works in his life, with more than 100 kinds. Among them, the most popular ones are "Tongya" and "Physical Knowledge". The former is a comprehensive noun collection, and the latter is a note. His scientific insights are mainly concentrated in this book. His later representative works are "Yaodi Cannon Village" and "Xingxia Jun", both of which are philosophical works, and some very important philosophical propositions are proposed in the book. Among his works, there are "Fushan Collection", "Boyi Collection", "Yi Yu", "Yi Constant Questions and Answers", "Chechuangyuanyuan", "Flowering Grass", "The Pictures of the Zhou Yi", "Natural Reason", "Learn Yi Gangzong", "School of the Sons of the Son", "Four Rhymes and Determination", "Inner Classics", "Medical Huitong", etc. There are more than 20 kinds of them.
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