There are all sorts of mills: some go by water, undershot or overshot; but if the millpond is dry, or the stream runs low, they come to a standstill. They want help, they must have water, to go on. Next there are steam-mills, which make a great noise and do a great deal of work; but they want coals and water too: if both are not brought to them, they stop and can do nothing. And then there are wind-mills; but everybody knows that wind-mills, though they do stand on the tops of hills, in spite of their great long arms stuck out, are of no use if the wind does not blow. So a man may try to do a great deal of work; but if he tries to get on without the help of his neighbours, and without being willing to help them in return, he will soon find that he too has to come to a standstill.