<span>Well, an arch is a type of symmetrical composite of two halves. These two halves *have* to be very precise they must be balanced. If they're not, the structure does will collapse.
Back to the proverb, the proverb basically means the arch can't 'sleep', 'relax', or take a day off.
President Woodrow Wilson spoke these words and was president during WWI. The phrase war to end all wars was actually coined by H.G. Wells in abook that he wrote. President Wilson is said to have used it later one time.
