In examining the role of Corax and Tisias in the development of rhetoric should be considered: (1) the recently-discovered transition from orality to literacy in the ancient Greek world, suggesting that rhetoric became a formal discipline at their hands through the medium of writing and that rhetoric existed in some form in the earlier oral culture; and (2) the religious crisis that occurred when the Syracusan tyrant Hieron was unable to exercise the religious authority required to rule, lending support to the view that Corax was a religious figure and that rhetoric existed in the earlier religious world. The gradual displacement of the old world of primary orality by the emerging world of literacy necessitated that traditional rhetoric as practiced in the oral culture be conceptualized according to new thought processes made possible by the new literacy and be expressed in the written form that literacy required for dissemination to the public. This transition implies that rhetoric existed in some form in the old oral world long before it became a "techne" (art of rhetoric). That form was probably religious in nature, as indicated by the evidence of Corax's religious role, i.e. religio-political advisor to the tyrant Hieron and logographer/etymologist (along with Tisias) engaged in divining the meaning of words. This suggests that the roots of rhetoric will be discovered in the religious world of oracular divination and of political life. (Thirty-four references are appended.) (MS)