RIO DE JANEIRO – The little man was running easily, his head as still as a museum statue’s, the heels of his running spikes brushing against the fluttering nylon of his running shorts in a sort of long distance ballet. Suddenly the little man was on the ground 10 laps into a 25-lap footrace, rolling to his side and then rising to chase the runners who were quickly pulling away from him. “Is the race done?” the little man asked himself. And then Mo Farah set out chasing the rest of the field for many wonderful reasons. “I worked too hard for this,” he said, and that was one of the reasons.