Once a sentry was guarding a palace. "Left! Right! Left! Right! he would mutter as he marched to and fro, thinking of his supper, which, being Thursday, would be roast beef and Yorkshire pudding. Had it been Friday, supper would be steamed fish. The soldier did not like that supper much.

     One day a naughty soldier tried to start a revolution.
     "Will you join me?" Today is Thursday. I could not miss supper of roast beef and Yorkshire pudding. If you had asked me on a Friday, I might have."

     All the other soldier's thought the same way and the revolution failed. Which shows that if you wish to start a revolution, you should pick your day carefully.