In regard to the prophets among the Jews, some of them were wise men before they became divinely inspired prophets, while others became wise by the illumination which their minds received when divinely inspired. They were selected by Divine Providence to receive the Divine Spirit, and to be the depositaries of His holy oracles, on the ground of their leading a life of almost unapproachable excellence, intrepid, noble, unmoved by danger or death. For reason teaches that such ought to be the character of the prophets of the Most High, in comparison with which the firmness of Antisthenes, Crates, and Diogenes will seem but as child's play.
Source: Translated by Frederick Crombie. From Ante-Nicene Fathers, Vol. 4. Edited by Alexander Roberts, James Donaldson, and A. Cleveland Coxe. (Buffalo, NY: Christian Literature Publishing Co., 1885.)