The document discusses the concept of concepts as objects of diachronic linguistics. It provides background on the theoretical bases of comparativism, including the hypotheses of monogenesis and proto-languages. It then outlines the methodology of comparative-historical language study, including using expanding circles and comparing data from written records. The document also discusses procedures of comparativistics like reconstruction and diachronic interpretation. Finally, it examines concepts as diachronic phenomena using the example of the mega concept represented by the English word "tea".