As he was going out, he reprimanded me pointedly and aloud. "I willingly pardon this child," said he; "he has offended only through ignorance. But you, sir, must have known the nature of his fault; why did you allow him to commit such a fault? Since you live together, you, who are older, ought to have taken the trouble of advising him; the authority of your experience should have guided him. When he is old enough to reproach you for his childish errors, he will certainly blame you for those of which you did not warn him."[4] He went away, leaving us greatly abashed. I took upon myself the blame of my easy compliance, and promised the child that, another time, I would sacrifice it to his interest, and warn him of his faults before they were committed. For a time was coming when our relations would be changed, and the severity of the tutor must succeed to the complaisance of an equal. This change should be gradual; everything must be foreseen, and that long beforehand. The following day we returned to the fair, to see once more the trick whose secret we had learned. We approached our juggling Socrates with deep respect, hardly venturing to look at him. He overwhelmed us with civilities, and seated us with a marked attention which added to our humiliation. He performed his tricks as usual, but took pains to amuse himself for a long time with the duck trick, often looking at us with a rather defiant air. We understood it perfectly, and did not breathe a syllable. If my pupil had even dared to open his mouth, he would have deserved to be annihilated. All the details of this illustration are far more important than they appear. How many lessons are here combined in one! How many mortifying effects does the first feeling of vanity bring upon us! Young teachers, watch carefully its first manifestation. If you can thus turn it into humiliation and disgrace, be assured that a second lesson will not soon be necessary. "What an amount of preparation!" you will say. True; and all to make us a compass to use instead of a meridian line! Having learned that a magnet acts through other bodies, we were all impatience until we had made an apparatus like the one we had seen,--a hollow table-top with a very shallow basin adjusted upon it and filled with water, a duck rather more carefully made, and so on. Watching this apparatus attentively and often, we finally observed that the duck, when at rest, nearly always turned in the same direction. Following up the experiment by examining this direction, we found it to be from south to north. Nothing more was necessary; our compass was invented, or might as well have been. We had begun to study physics. Experimental Physics.