Now one of the most difficult tasks of the criminalist is to hit, in just such cases, upon the truth; neither to accept the testimony blindly and uncritically; nor to render the witness, who otherwise is telling the truth, vacillating and doubtful. But it is still more difficult to lead the witness, who is not intentionally falsifying, but has merely observed incorrectly or has made false conclusions, to a statement of the truth as Socrates leads the slave in the Meno. It is as modern as it is comfortable to assert that this is not the judge’s business--that the witness is to depose, his evidence is to be accepted, and the judge is to judge. Yet it is supposed before everything else that the duty of the court is to establish the material truth--that the formal truth is insufficient. Moreover, if we notice false observations and let them by, then, under certain circumstance, we are minus one important piece of evidence _pro_ and _con_, and the whole case may be turned topsy turvy. At the very least a basis of development in the presentation of evidence is so excluded. We shall, then, proceed in the Socratic fashion. But, inasmuch as we are not concerned with mathematics, and are hence more badly placed in the matter of proof, we shall have to proceed more cautiously and with less certainty, than when the question is merely one of the area of a square. On the one hand we know only in the rarest cases that we are not ourselves mistaken, so that we must not, without anything further, lead another to agree with us; on the other hand we must beware of perverting the witness from his possibly sound opinions. It is not desirable to speak of suggestion in this matter, since, if I believe that the other fellow knows a matter better than I and conform to his opinion, there is as yet no suggestion. And this pure form of change of opinion and of openness to conviction is commonest among us. Whoever is able to correct the witness’s apparently false conceptions and to lead him to discover his error of his own accord and then to speak the truth--whoever can do this and yet does not go too far, deducing from the facts nothing that does not actually follow from--that man is a master among us. Section 2. (b) The Method of Natural Science.[40]