Now Clement, having succeeded Pantaenus, was at that time presiding over the catechizing at Alexandria, so that Origen too became one of his pupils. Indeed Clement, when compiling his work the Stromateis, in the first treatise sets forth a chronological table and brings down the dates to the death of Commodus, so that it is plain that the work was laboured over by him under Severus, whose times the present account is recording.