teach be? for it will render the manner in which a thing subsists evident to him who neither considered, nor knew, nor supposed that it is predicated in another way. Since what prevents this also being done in things which are not double? are then unities equal to duals in four? but the duals are inherent, some in this, but others in that way. Is there also one science of contraries or not? but some contraries are known, others unknown: so that he appears to be ignorant, who requires this, viz. that to teach is different from to discuss, and that it is necessary that the teacher should not interrogate, but himself declare, but that the other should interrogate.
Chapter 11
Moreover, to postulate affirmation or denial is not the province of one who demonstrates, but of him who makes a trial, for the peirastic art is a certain dialectic, and considers not the scientific, but him who is ignorant, and who pretends. Whoever therefore considers things which are common really, is a dialectician, but he who does this apparently, is a sophist; the contentious and sophistical syllogism also are, one indeed, apparently syllogistic about things with which the peirastic dialectic is conversant, although the conclusion be true, for it deceives in assigning the why, and (in the other kind are those paralogisms), which not being according to the method of each thing, seem to be according to art. For false descriptions are not contentious, (since paralogisms are according to those things which are subject to art,) neither even if there is a certain false description about the true (conclusion), as that of Hippocrates, viz. the quadrature of the circle through lunulæ, but as Bryso squared the
