The Stoics, uncompromising as they were in their conception of the physical world as a continuum, supposed that "beyond the cosmos there stretches an infinite, non-physical void". This empty space played an important part in their cosmogony, for the following reason. At the end of every cosmic cycle, when the hot element becomes predominant, the cosmos expands thermically and thus increases in volume. Now, the problem raised by this increase in volume can be solved, if the cosmos is, as assumed, an island in an infinitive void. The pupils of Aristotle, who, like their master, maintained that the cosmos was finite and denied the infinite extension of space, rejected this Stoic theory. The whole question became the subject of a scientific controversy between the two schools which bears a remarkable resemblance to the modern cosmological argument about space and the structure of the matter in it.