Abstract
The article deals with currents and tides. We look at the history of their observation in antiquity as well as alternative theories, designed to explain their nature. Major theories accessed are those by Aristotle, Posidonius and Seneca. Special attention is given to ancient explanation of the phenomenon of the periodical change of the stream in Euripus’ channel. Throughout we refl ect on an analogy between natural phenomena and the processes occurring in living organisms, common to our philosophers of nature, as well as the peculiarities of their interpretation of the theory of mutual transformation of the elements. Besides, it is important to note the place of the method of analogy in their observations and theoretical constructions.