"But how can they? How can two thin sheets of muslin keep cold out or heat in, which I believe is the better way of putting it?" asked Harry.
"They can't," answered the Doctor. "Bring those two sheets of muslin together and they would let heat out and cold in as freely almost as an open hole does. It isn't the muslin that keeps the cold out or the heat in—which ever way you choose to put it. It is the imprisoned air between the two pieces of muslin. There is hardly anywhere a worse conductor of heat than confined air. That is why in building fire proof structures in the great cities they use hollow bricks for partition walls. No amount of heat on one side can pass through the confined air in the bricks and set fire to anything on the other side of the wall. In the contracts for such buildings it is often stipulated that the owner shall be free to build as hot a bonfire as he pleases in any room he may select, and if it sets fire to anything in any other room the contractor shall pay a heavy penalty."
"But where did you get your idea of greased muslin windows, Doctor?" asked Jack. "I never heard of it before."
"I got it by reading history," answered the Doctor. "In old English times nobody but princes could afford to use glass. Its cost was too great. And then later, when glass became cheaper, a stupid government put a tax on windows, and so men went on using greased cloth instead of glass in order to get the light of heaven into their habitations without having their substance eaten up by a window tax."
"But why was it 'stupid' as you say for the government to raise revenue by so simple a means as that of taxing windows?" asked Jack.
"Because governments exist for the good of the people governed, and not the reverse of that. Otherwise no government would have any right to exist at all. A window tax discourages the use of windows. As a result the people live in darkness and foul air, which is not good for them. But governments in the old days assumed not that the government existed for the good of the people, but that the people existed for the good of the government. Never until our American Republic was established was that notion driven out of the minds of Kings, Princes and great ministers of state. It is one of our country's best services to human kind that it has taught this lesson until now in every part of the civilized world it is perfectly understood that the government is the servant of the people, not the people the servant of the government."
"Yes, I remember," said Jack, "that when the colonies were resisting British oppression, Thomas Jefferson put into an address to George III a pointed and not very polite reminder that the King was after all only a chosen chief magistrate of the people, appointed by them to do their service and promote their happiness. There wasn't much idea of 'the divine right of kings' in Jefferson's noddle."
"No," responded the Doctor, "nor in Franklin's, or Patrick Henry's or John Adams's or James Otis's. Jefferson simply formulated the thought of all of them when he contended that the British parliament had no more right to pass laws for the government and taxation of Virginia than the Virginia legislature had to pass laws for the government and taxation of Great Britain. But the beauty of the whole thing lies in the fact that these great truths, asserted by the Americans in justification of their rebellion, have been fastened upon the minds of men everywhere, and all civilized governments have been compelled to accept and submit to them. There are kings and emperors still, but they have completely changed their conception of their functions. They have been taught, mainly by American statesmen, that they are nothing more than the servants of the people, and that so far from owning the people, the people are their masters. But come boys, it's time to get to bed. So turn in at once. I'm on guard for the next hour and a half."