is contentious, and it is impossible to refer the one except to geometry alone from its being from the proper principles, but (we may refer) the other to many who do not know what is possible and impossible in each thing, for it will accord. Or as Antipho squared the circle, or if a man should not grant it is better to walk after supper on account of the argument of Zeno, it is not medical, for it is common. If then, the contentious person subsists altogether with reference to the dialectician, as he who makes a false description does to the geometrician, there would not be a contentious syllogism about those; now however the dialectician is not in any definite genus, nor does he demonstrate any thing, nor is he such as the universal (philosopher). For neither are all things in one certain genus, nor if they were, is it possible that beings should be under the same principles, so that none of those arts which demonstrate a certain nature is interrogative, for it is not possible to grant each of the parts, for a syllogism does not arise from both. Dialectic however is interrogative, but if it should demonstrate, though not all things, yet it would not interrogate primary things and proper principles; for there being no concession, he would no longer have arguments from which he could discourse against the objection. It is also peirastic, for neither is the peirastic art such as geometry, but even an unscientific man may possess it, since it is possible that he who is ignorant of a thing may make trial of one who is ignorant, if he concedes not from what he knows, nor from properties, but from consequents, which are such as there is nothing to prevent him who knows them, not knowing the art, but it is necessary that he who does not know them, must be ignorant (of the art). Wherefore, it is evident that the peirastic art is the science of nothing definite; hence also, it is conversant with all things, since all arts use certain common things, on
