The Encheiridion, or Manual (51-53)

How long will you then still defer thinking yourself worthy of the best things, and in no matter transgressing the distinctive reason?[*] Have you accepted the theorems (rules), which it was your duty to agree to, and have you agreed to them? what teacher then do you still expect that you defer to him the correction of yourself? You are no longer a youth, but already a full-grown man. If then you are

The first and most necessary place (part, τόπος) in philosophy is the use of theorems (precepts, φεωρήματα), for instance, that we must not lie: the second part is that of demonstrations, for instance, How is it proved that we ought not to lie: the third is that which is confirmatory of these two and explanatory, for example, How is this a demonstration? For what is demonstration, what is consequence, what is contradiction, what is truth, what is falsehood? The third part (topic) is necessary on account of the second, and the second on account of the first; but the most necessary and that on which we ought to rest is the first. But we do the contrary. For we spend our time on the third topic, and all our earnestness is about. it: but we entirely neglect the first. Therefore we lie; out the demonstration that we ought not to lie we have ready to hand.