Epictetus

“ That is an excellent answer of Diogenes to the man who asked for a letter of recommendation from him: "That you are a man," he says, "he will know at a glance; but whether you are a good or a bad man he will discover if he has the skill to distinguish between good and bad, and if he is without that skill he will not discover the facts, even though I write him thousands of times." ”

“ If the man in question is an assayer of silver, you will recommend yourself. We ought, therefore, to have also in everyday life the sort of thing that we have in the case of silver, so that I may be able to say, as the assayer of silver says, "Bring me any drachma you please, and I will appraise it." Now in the case of syllogisms I say, "Bring me any you please and I will distinguish for you between the one that is capable of analysis and the one that is not." [1] How so? Because, I know how to analyze syllogisms myself ”