International audienceThis book presents the outcomes of an innovative research program in the history of science. It relies on the study of a broad range of documents of the past, dealing with various domains: mathematics, zoology, medicine, lexicography. The documents examined were written in different parts of the world: China, Europe, India, Mesopotamia. The book implements a Text Act Theory, which extends Speech Act Theory, in order to illustrate a new approach to texts and textual communicative acts. It examines assertives (of various kinds: absolute or conditional statements, forecasts, insurance, etc.), directives, declarations, enumerations, etc., as well as different types of textual units allowing authors to perform these acts: algorithms, recipes, prescriptions, lexical templates for terminological studies, enumerative structures, etc. The importance of the results obtained in both history of science and Text Act Theory suggests that the approach will prove fruitful in the long term