EN
The study explores the meaning and function of two categories of signs (semeia and tekmeria) which were coordinated in an established argumentation figure in the texts of the orators and rhetorical teachers (Antiphon, Lysias, Isocrates, and the anonymous collection of arguments Dissoi logoi) on the one hand, and in the Hippocratic medical handbook Prognosticon on the other. These texts were written at the end of the 5th century B.C. and at the beginning of the next. Discussing all occurrences of the figure, the study formulates the functional relationship between the two types of signs, which is valid in an analogous way both for rhetoric and for a medical prognosis. Contrariwise to the later known Aristotelian classification of semeia and tekmeria, the distinction in older texts is not rooted in logic (analytics in Aristotelian sense), but it is related to dialectic or eristic. The study provides an addendum to the recent commented edition of Prognosticon by Jacques Jouanna, where the distinction is not adequately treated.