There are several interesting accounts of these Sophists in extant literature, but the writers are always prejudiced opponents. In the _Clouds_ of Aristophanes, the Sophists and their pupils are represented as living in an underground Thinking-Shop. They are pale and squalid, engaged in all sorts of researches. Natural history is represented by the important question, “How many times the length of its own foot does a flea jump?” a problem which is solved by actual experiment. Later in the play they inquire why the sea does not overflow, since the rivers are always running into it. Scientific instead of mythological explanations of thunder and lightning are given. There is religious criticism too, such as Xenophanes had uttered long before: “If Zeus imprisoned his own father, why has he not been punished?” There is astronomy, “the paths and orbit of the sun,” and a hanging basket is introduced as an observatory. Geometry and compasses are mentioned. The visitor is shown a map of the world, containing Euboia, Lakedaimon, and Attica on a large enough scale, it would seem, to mark the deme Kikunna; perhaps, as Strepsiades expects to find dikastai on it at Athens, it had pictures of elephants and monsters in unknown districts. The students are interested in metres and rhythms. The poet laughs at grammar, forming “cockess” as the logical feminine of cock, and making the chief Sophist object to feminine nouns with masculine terminations. It is suggested that the pupils at the Thinking-Shop are dirty, half-starved vegetarians, too economical to go to the hair-cutter or the baths, abstaining from wine and the gymnasia. But the main point attacked by Aristophanes is the teaching of Argument. The whole object of learning under the Sophists is, according to him, to be able to cajole the dikastai and so win impunity to cheat, and to have an argument to justify anything. The successful scholars beat their fathers and mothers, giving logical reasons for their behaviour; they refuse to go to school, and are too clever to believe or accept anything. But their intellectual exhilaration is spasmodic; they have been taught, if they reach a difficult problem, to jump on to something else. A vivid sketch of Sophist-life is given in Plato’s _Protagoras_. Young Hippokrates, on returning to Athens in the evening after pursuing a runaway slave to the frontier, hears that Protagoras the great Sophist has arrived in the city. Only the lateness of the hour deters him from rushing off to find Sokrates, who will give him an introduction to the teacher. Next morning he comes round to Sokrates’ house long before it is light, bangs and shouts at the door in his excitement, and announces that he is ready to spend all the money which he and all his friends possess, in fees.