A man must think of everything, figure on everything, from the grand sweep of the country at large to the pressure on a king-bolt.

And where another possesses the boundless resources of a great city, he has to rely on the material stored in one corner of a shed.

It is easy to build a palace with men and tools; it is difficult to build a log cabin with nothing but an ax.

His wits must help him where his experience fails; and his experience must push him mechanically along the track of habit when successive buffetings have beaten his wits out of his head.

In a day he must construct elaborate engines, roads, and implements which old civilization considers the works of leisure.