 As Victor Caston has argued, talk about supervenience should here be taken in the technical sense of a co-variation of mental states with bodily states (Caston 1997: 348–349). Moreover, Caston emphasizes that, for Alexander, the soul possesses causal powers that are more than the aggregates of the causal powers of the elements (1997: 349–350). In the sense that Alexander ascribes distinct new powers to souls as well as to the forms of non-animate composites such as chemical blends, Caston characterizes Alexander as one of the ancient thinkers who were committed to emergentism (1997).