Pagan writers in their published works passed spiteful and contemptuous judgments upon Christians and Christianity (Tacitus, Pliny, Marcus Aurelius, and the physician Galen), or, like the rhetorician Fronto, argued against them with violent invective; while popular wit ran riot in representing Christianity by word and picture as the devout worship of an ass. But even the talented satirist Lucian of Samosata was satisfied with ridiculing the Christians as senseless fools. The first and also the most important of all really pagan advocates was Celsus, who in the second century, with brilliant subtlety and scathing sarcasm sought to prove that the religion of the Christians was the very climax of unreason. In respect of ability, keenness and bitterness of polemic he is closely followed by the Neo-platonist Porphyry. Far beneath both stands Hierocles, governor of Bithynia. Against such attacks the most famous Christian teachers took the field as Apologists. They disproved the calumnies and charges of the pagans, demanded fair play for the Christians, vindicated Christianity by the demonstration of its inner truth, the witness borne to it by the life and walk of Christians, its establishment by miracles and prophecies, its agreement with the utterances and longings of the most profound philosophers, whose wisdom they traced mediately or immediately from the Old Testament, and on the other hand, they sought to show the nothingness of the heathen gods, and the religious as well as moral perversity of paganism.