The fourth period is related to establishing of Comparative Typology as a separate science with the bulk of General Linguistics. It coincides with the XX century.
The science of linguistic comparison was developing quite slowly and a number of factors played an important role to foster that process. They were also suggested by Dr Buranov.
The first factor istypological imitation, means using identified style or form of languages to explain another language. For example, the first Latin grammar "De Lingua Latina" (117-27 ВС) by Varron was written with the use of the ancient Greek language grammars compiled by Greek philosophers. His great contributions were changing 5 cases in Greek into 6 and 8 parts of speech into 7 in English.
Later, the grammar of European languages was shaped based on Latin and Greek languages. Besides, nowadays not only grammar but poetic speech and other language units are still based on Greek grammar.
Also while studying certain categories of one language scholars very often use the models of more researched languages, e.g. the ancient Indian models of compound words are used to describe many European languages
The second factor is characterized as a period of the appearance of scientific comparative works. Comparisons of languages and linguistic units date back to ancient period. Comparisons were scripted in “Port Royal Grammar” where ancient scholars such as Arnauld A., Lancelot C, analyzed similarities and differences between French, Latin, Greek and ancient Jewish languages. They have found out that out of these languages ancient Jewish language did not share substantial similarity with other languages. The Port Royal Grammar was extremely popular and gave an impetus to rapid development of comparative studies.
Until recent times, this book has been used in modern typology. N. Kretsman pointed out this book’s importance and said: “In the last seven or eight years the “Port Royal Grammar” has been discussed more often in the English speaking world than at any other time since its publication more than three hundred years ago”.
Comparative Linguistics that dealt with comparing of language units and languages that did not share common root language played an important role in the emerging and developing of this subject. Comparison of structural languages that were not substantial also was crucial in the development of Comparative Linguistics.