At both levels of scientific attainment, the modern as the classical, there has always been the cognizance of the formidable difficulties which are rooted in the fact that time as a continuous extension presupposes the existence of an extensionless instant, a dividing mark within the continuum, whereas immediate awareness of perpetual change associated with time renders that concept of a pointlike "now" null and void. In Greek antiquity it was again the Stoics who, by virtue of their dynamic notion of the continuum, succeeded more than anyone else during the whole period to develop a satisfactory theory of the structure of time and to present a lucid analysis of the nature of its ultimate elements. The significance of this theory of the Stoics will become more evident when seen against the background of the attainments of their predecessors.