Galen also makes use of a further set of causal categories, which are derived partly from the Stoic philosophical and partly from the medical tradition. Of particular importance—especially in medical contexts—are the concepts of “antecedent” (prokatarktikai) and “preceding” (proēgoumenai) causes; the further category of “containing” or “cohesive” (sunektikai) causes is also discussed. (Galen devoted two works explicitly to these causal concepts, CP and CC; see further Hankinson 1994b, 2008a.) While rejecting the specific Stoic theory to which this last category belongs, namely that objects require this type of cause as explanation of their persistence, Galen employs the concept to a limited extent, allowing that something productive of a particular effect, and co-temporal with that effect, may be considered its “containing cause”; he finds the category of some value for example in the analysis of the pulse.