"The debates in the Assembly, the trials before the heliaea, and the rising need for the ability to think with the appearance of logic and to speak with clarity and persuasion, conspired with the wealth and curiosity of an imperial society to create a demand for something unknown in Athens before Pericles—formal higher education in letters, oratory, science, philosophy, and statesmanship. The demand was met at first not by the organization of universities but by wandering scholars who engaged lecture halls, gave there their courses of instruction, and then passed on to other cities to repeat them. Some of these men, like Protagoras, called themselves sophistai—i.e., teachers of wisdom. The word was accepted as equivalent to our “university professor,” and bore no derogatory connotation until the conflict between religion and philosophy led to conservative attacks upon the Sophists, and the commercialism of certain of them provoked Plato to darken their name with the imputations of venal sophistry that now cling to it... It is true that the more famous Sophists, like most skilled practitioners in any field, charged all that their patrons could be persuaded to pay; this is the final law of prices everywhere."