When studying functions of ostracism, it is necessary to distinguish between different as- pects of the problem. The functions in question did not remain invariable but were subject to considerable changes. The idea of ostracism as a «preventive» banishment of influential per- sons arose as early as in the Archaic epoch, on the verge of two political trends in early Greek polis, individualistic and collectivist ones. The early forms of ostracism (which can be called «pre-ostracism», as it was not the assembly, but various aristocratic boulai that took decisions about it) were a means of mutual control used by members of the ruling noble elite in order to prevent any one of them from becoming a tyrant. As to the Kleisthenes' law of ostracism, which was established in Athens in 508/7 ВС and submitted turned over the procedure to the competence of the assembly, this law must be considered within the whole complex of Kleis- thenic reforms which passed the supreme power in the polis from aristocracy to the people. The latter adopted the institution that had an aristocratic origin. Since then the Athenian dem- os became the main guarantor against revival of tyranny and against sharp outbursts of stasis; by means of ostracism it also controlled activities of its noble elite. All this corresponded to the new role of the people in the Athenian State. Furthermore, ostracism, being rather a mild and humane measure, helped to regulate political strife, which had often taken brutal forms before. However, later, in the course of the 5th century ВС, ostracism acquired several new func- tions, which even became to some extent predominant and moved aside the original ones. Ri- valing political leaders used ostracism as a powerful tool for struggle with each other. On the other hand, the demos began to consider ostracism as a way of choice between leaders (espe- cially when there were two competing leaders) and their lines, particularly in the field of for- eign affairs. Ostracism also became a convenient means for compensating for the collective frustration within the community under the conditions of direct democracy. Thus, ostracism was a democratic institution of an aristocratic origin. It retained its traditional orientation against representatives of the highest elite. In this sense it was a measure, if not honorary, in any case underlining the authority of the politicians who became its victims.