Suppose we are studying the course of the sun and the way to find our bearings, when all at once Emile interrupts me with the question, "What is the use of that?" what a fine lecture I might give, how many things I might take occasion to teach him in reply to his question, especially if there is any one there. I might speak of the advantages of travel, the value of commerce, the special products of different lands and the peculiar customs of different nations, the use of the calendar, the way to reckon the seasons for agriculture, the art of navigation, how to steer our course at sea, how to find our way without knowing exactly where we are. Politics, natural history, astronomy, even morals and international law are involved in my explanation, so as to give my pupil some idea of all these sciences and a great wish to learn them. When I have finished I shall have shown myself a regular pedant, I shall have made a great display of learning, and not one single idea has he understood. He is longing to ask me again, "What is the use of taking one's bearings?" but he dare not for fear of vexing me. He finds it pays best to pretend to listen to what he is forced to hear. This is the practical result of our fine systems of education.
But Emile is educated in a simpler fashion. We take so much pains to teach him a difficult idea that he will have heard nothing of all this. At the first word he does not understand, he will run away, he will prance about the room, and leave me to speechify by myself. Let us seek a more commonplace explanation; my scientific learning is of no use to him.
We were observing the position of the forest to the north of Montmorency when he interrupted me with the usual question, "What is the use of that?" "You are right," I said. "Let us take time to think it over, and if we find it is no use we will drop it, for we only want useful games." We find something else to do and geography is put aside for the day.
Next morning I suggest a walk before breakfast; there is nothing he would like better; children are always ready to run about, and he is a good walker. We climb up to the forest, we wander through its clearings and lose ourselves; we have no idea where we are, and when we want to retrace our steps we cannot find the way. Time passes, we are hot and hungry; hurrying vainly this way and that we find nothing but woods, quarries, plains, not a landmark to guide us. Very hot, very tired, very hungry, we only get further astray. At last we sit down to rest and to consider our position. I assume that Emile has been educated like an ordinary child. He does not think, he begins to cry; he has no idea we are close to Montmorency, which is hidden from our view by a mere thicket; but this thicket is a forest to him, a man of his size is buried among bushes. After a few minutes' silence I begin anxiously——
JEAN JACQUES. My dear Emile, what shall we do get out?
EMILE. I am sure I do not know. I am tired, I am hungry, I am thirsty. I cannot go any further.
JEAN JACQUES. Do you suppose I am any better off? I would cry too if I could make my breakfast off tears. Crying is no use, we must look about us. Let us see your watch; what time is it?
EMILE. It is noon and I am so hungry!
JEAN JACQUES. Just so; it is noon and I am so hungry too.
EMILE. You must be very hungry indeed.
JEAN JACQUES. Unluckily my dinner won't come to find me. It is twelve o'clock. This time yesterday we were observing the position of the forest from Montmorency. If only we could see the position of Montmorency from the forest.
EMILE. But yesterday we could see the forest, and here we cannot see the town.
JEAN JACQUES. That is just it. If we could only find it without seeing it.
EMILE. Oh! my dear friend!
JEAN JACQUES. Did not we say the forest was…
EMILE. North of Montmorency.
JEAN JACQUES. Then Montmorency must lie…
EMILE. South of the forest.
JEAN JACQUES. We know how to find the north at midday.
EMILE. Yes, by the direction of the shadows.
JEAN JACQUES. But the south?
EMILE. What shall we do?
JEAN JACQUES. The south is opposite the north.
EMILE. That is true; we need only find the opposite of the shadows. That is the south! That is the south! Montmorency must be over there! Let us look for it there!
JEAN JACQUES. Perhaps you are right; let us follow this path through the wood.
EMILE. (Clapping his hands.) Oh, I can see Montmorency! there it is, quite plain, just in front of us! Come to luncheon, come to dinner, make haste! Astronomy is some use after all.
Be sure that he thinks this if he does not say it; no matter which, provided I do not say it myself. He will certainly never forget this day's lesson as long as he lives, while if I had only led him to think of all this at home, my lecture would have been forgotten the next day. Teach by doing whenever you can, and only fall back upon words when doing is out of the question.
The reader will not expect me to have such a poor opinion of him as to supply him with an example of every kind of study; but, whatever is taught, I cannot too strongly urge the tutor to adapt his instances to the capacity of his scholar; for once more I repeat the risk is not in what he does not know, but in what he thinks he knows.
I remember how I once tried to give a child a taste for chemistry. After showing him several metallic precipitates, I explained how ink was made. I told him how its blackness was merely the result of fine particles of iron separated from the vitriol and precipitated by an alkaline solution. In the midst of my learned explanation the little rascal pulled me up short with the question I myself had taught him. I was greatly puzzled. After a few moments' thought I decided what to do. I sent for some wine from the cellar of our landlord, and some very cheap wine from a wine-merchant. I took a small43 flask of an alkaline solution, and placing two glasses before me filled with the two sorts of wine, I said.
Food and drink are adulterated to make them seem better than they really are. These adulterations deceive both the eye and the palate, but they are unwholesome and make the adulterated article even worse than before in spite of its fine appearance.
All sorts of drinks are adulterated, and wine more than others; for the fraud is more difficult to detect, and more profitable to the fraudulent person.
Sour wine is adulterated with litharge; litharge is a preparation of lead. Lead in combination with acids forms a sweet salt which corrects the harsh taste of the sour wine, but it is poisonous. So before we drink wine of doubtful quality we should be able to tell if there is lead in it. This is how I should do it.
Wine contains not merely an inflammable spirit as you have seen from the brandy made from it; it also contains an acid as you know from the vinegar made from it.
This acid has an affinity for metals, it combines with them and forms salts, such as iron-rust, which is only iron dissolved by the acid in air or water, or such as verdegris, which is only copper dissolved in vinegar.
But this acid has a still greater affinity for alkalis than for metals, so that when we add alkalis to the above-mentioned salts, the acid sets free the metal with which it had combined, and combines with the alkali.
Then the metal, set free by the acid which held it in solution, is precipitated and the liquid becomes opaque.
If then there is litharge in either of these glasses of wine, the acid holds the litharge in solution. When I pour into it an alkaline solution, the acid will be forced to set the lead free in order to combine with the alkali. The lead, no longer held in solution, will reappear, the liquor will become thick, and after a time the lead will be deposited at the bottom of the glass.
If there is no lead44 nor other metal in the wine the alkali will slowly45 combine with the acid, all will remain clear