Gaius (about 130~180) was a famous jurist in the early stage of the Roman Empire and the earliest born of the so-called "five great Roman jurists". The name of the ancient Romans consists of three names, with Gaius as its first surname. As a law teacher, he is the first professional jurist in the world who has a professional treatise handed down. Academically, Gaius claimed to belong to the Sabinism. He is a prolific jurist, and has 13 kinds of works, such as the Annotation of the Twelve Copper Tables, 32 Commentaries on the Provincial Decree, 15 Commentaries on the Municipal Magistrate's Notice, 15 Commentaries on the Law, 1 commission theory, case theory, rule theory, graft theory, and 1 mortgage theory.

His representative work is undoubtedly the four-volume "Institutes of Law". This book is not only the textbook of the law school at that time, but also the model of Justinian's compilation of the code "Ladders of Law" (one of the Roman "Complete Collection of National Laws") of the same name, but also a complete document of ancient Roman jurists that has been handed down to later generations. In addition, it is also the first legal monograph in the strict sense in the history of western law. Before it, the ancient Greek scholar Plato's Law, Aristotle's Political Science, and the ancient Roman scholar Cicero's On Law failed to strictly distinguish law from politics, philosophy, theology and other topics. Gaius' treatise studies legal phenomena from the perspective of pure law. Its complete transmission to later generations is also due to the popularity of the book to a certain extent. The book, which was completed around 161 A.D., is a primary law textbook and has been used as a textbook for Roman law students for a long time. The content of private law has almost been covered, and it is suitable for law schools and citizens to study law by themselves. Therefore, the book was widely circulated at that time. In addition to the "Ladder of Law", Gaius also compiled a "Daily Legal Events", which was called "the Golden Book" by later scholars, and is a book that further elaborates the "Ladder of Law". Unfortunately, this explanatory book has been lost. Because Gaius and other jurists wrote about the rights of the emperor and maintained the ruling order of the empire at that time, in 426 AD, the eastern Roman emperor Theodosius II and the western Roman emperor Valentin II issued the Law of Proof of Doctrine. Gaius, together with Pabinian, Urbian, Paul, and Modine, was listed as the five greatest jurists of Rome, and Gaius was second only to Urbian and Pabinian. In the sixth century AD, there were 535 articles in the Compilation of Theories by Justinian, the East Roman emperor, selected from Gaius's Ladder of Law. The principle of "a person's house is his barrier" pursued by the West today is from Gaius

From the analysis of the general situation of the Roman Republic and the early stage of the Roman Empire, before the 2nd century AD, Roman jurists were initially limited to sorting out and possibly sorting out the previously enacted laws, without adding anything of their own; In the subsequent development stage, jurists added litigation and their interpretation beside the law, which is likely to be explanatory; Since then, jurists have incorporated the comments on the law into a general system based on their knowledge, and studied the law by means of classification, induction and deduction as well as systematic methods, thus laying the foundation of civil law; Later works all follow the "systematic and creative" approach, that is, in the discussion, sometimes it is shown as the investigation of the contents of the notice, sometimes it is shown as the investigation of the contents of the law, the resolution of the senate or the decree of the monarch, sometimes it is shown as the discussion of the opinions of the previous jurists, the examples compiled to reflect the colorful side of a certain problem, or the specific cases requiring the jurists to express their opinions, This method is always guided by a profound internal system, and always uses induction and deduction as much as possible, supplemented by other argumentation methods based on universally accepted principles. Different from the methods adopted by these Roman jurists, what is known in Gaius' works is the requirements of teaching, which reduces the creative elements and increases the narrative elements of the fixed law; The systematic method is paid attention to there, which is also clearly reflected in the narrative order that makes people easy to understand and remember. He made great efforts to form an internal system in the book of system theory. At that time, the order of other jurists' works was closely related to the activities of the parties who concluded the legal act and the plaintiffs on the litigation stage. Gaius was one step ahead of them, and he carried out the investigation of the content of rights very early. In his system, issues such as people, things, litigation (i.e., rights concerned from the perspective of people), people's enjoyment of things, and the enjoyment of rights and legal relations (also examining the content, acquisition and loss of these rights and relations) are put at the top of the list, fully reflecting the legal concept of taking people as the center and making rights serve people. It can be said that Gaius' system was created based on the model of equal, sovereign and property fathers and their mutual relations in reality, which endows civil law with characteristics; These fathers represent the ideal people and their central position in the law. This trend of thought in law undoubtedly echoes the idea of "everyone should be brothers and friendly to each other" advocated in the then popular Neostoicism philosophy.

The representative of the famous jurist in the early stage of the Roman Empire is the Ladder of Law, which is a popular document of ancient Roman jurists and becomes a model for Justinian to compile the code of the same name.
Literature characteristics
1. Maintain the basic position of Sabin. According to the previous analysis, Gaius pays attention to the civil law of the city, taking the civil law of the city as the main research object, supplemented by the law of the Lord Chancellor and the civil law of the people; In terms of methodology, it pays attention to the spirit of evolution, opposes traditional formalism, and is not limited to the provisions of laws and regulations.
2. The content is concise, very popular and complete. Its sentences are concise, incisive and concise.
3. Pragmatic spirit: value reality rather than theory. According to the previous analysis, when there are contradictions and conflicts between theory and practice, Gaius often abandons the requirements of theory and devotes himself to meeting the actual needs. Due to the limitation of the level of economic and cultural development at that time, legal practice was not enough to generalize many important legal relations contained in the phenomenon into general principles in theory. Like other Roman jurists, he believed that all concepts and definitions were not enough to adapt to the rapid development of the situation. "All definitions are dangerous in law". This shows a sign of his realistic spirit. In addition to clarifying the views of his own school, he often quotes the views of the other school, and can correct his own school's views when he is sure that there is a mistake. He does not overshadow and persist in mistakes because of the differences between the schools, which shows the good academic research trend of seeking truth in fact.
4. Innovative spirit: According to the analysis of the previous article, Gaius has introduced the three-part structure of human law, material law and procedural law in this book, and the material law is described in two volumes. The division of Roman private law into three parts, namely, human law, material law and procedural law, has basically established the structural system of modern civil law. In addition, he was the first to put forward the famous assertion that "there is no distinction between tangible and intangible rights" in this book.
deficiencies
1. The understanding of law is not comprehensive enough, especially the content of material law and procedural law has not formed a complete theoretical system.
2. Lack of the abstract thinking ability possessed by the Greeks, and some chapters and paragraphs are described upside down, which does not conform to the reading habits of modern readers.
3. Due to the excessive pursuit of simplicity, most of the time is to introduce the Roman legal system and the general theory of the theoretical circle, which does not fully reflect their own ideas. Moreover, his writing lacks literary grace, and his literary quality and artistic attainments are not as good as those of Plato and Aristotle in ancient Greece, nor as those of Cicero at the end of the Roman Republic, let alone compare it with the great thinkers of modern times such as Grotius, Montesquieu and Beccaria. Of course, this is a common feature of many ancient Roman jurists.
4. Oppose the rule of law and support the rule of man. In his exposition, Gaius still defended the slavery of Rome and the autocracy of the Roman Empire. As Gaius explained the "decree of the monarch" mentioned above (he believed that the decree of the monarch had legal effect because the emperor himself obtained the ruling power according to the Royal Power Law), which put a legal coat on the rule of the emperor and the rule of man. For example, in paragraphs 14 and 15 of the first volume of the book, he called all the losers who participated in the war against the Roman Community as "surrender", and said that participating in the revolt was "doing a bad thing", and banned such people from becoming Roman citizens and Latinos, in an attempt to maintain the autocratic rule of the Roman Empire in theory.
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