=173.= The fact that the Stoics use from time to time the language of other schools or of popular speculation does not necessarily imply that this language is an adequate statement of their doctrine; and we frequently[4] find that the discussion of particular problems seems to be based on dualisms, though these are in the end subordinated to monistic statements. Thus in logic we have already noticed the sharp contrast between the perceiving mind and the external object of perception (αἰσθητόν, ὑπάρχον); nevertheless mind and object are ultimately declared to be akin[5]. So in particular the popular dualism of ‘soul’ and ‘body’ is often accepted by the Stoics, and yet as steadily superseded by the paradox that ‘soul is body.’ The reason given for this is that ‘body is that which acts and is acted upon[6]’; and this statement in the end overrides the Aristotelian distinction of force and matter, active principle and passive principle. ‘Body,’ as conceived by the Stoics, is the one ultimate element, the foundation and beginning of the universe; it contains within itself the capacity of action, and nothing but ‘body’ has this capacity. Body, and nothing but body, exists in the true sense; that certain other things have a quasi-existence (as we shall see later in this chapter) is an embarrassment which only brings into clearer relief this distinctive feature of the system. The Stoic ‘body,’ though it is also called ‘matter’ (ὕλη, _materia_), must not be confused with the ‘matter’ of modern philosophy, which has derived from Aristotle the implication of passivity[7]; much more closely it corresponds with the ‘stuff’ by which modern monistic philosophers denote the substratum of mind and body alike. To call the Stoics ‘materialists’ will generally prove misleading; it is the Epicurean system, to which the Stoics were sharply opposed, which (as we have seen)[8] corresponds to modern materialism. [Sidenote: The nature of ‘body.’]