Newton invited a friend to dinner. The friend came on time. The food was set, but Newton was still at work. The friend knew Newton’s habits, sat around the table and waited. After a long time, the food was cold, still did not see Newton, the friend had to eat first. After eating, he suddenly had an idea, to play a small joke on Newton. So, he put the chicken bones into the plate, put the cover on, then went quietly. He concluded his practical joke would work. It was already deep at night, having worked most of the day, Newton suddenly felt a little hungry. He put down the work and went into the dining room for dinner. He opened the dishes, there were chicken bones, Newton felt very strange, how was this going? He turned around and had a look at the clock, the dinner time had passed. He seemed to know something: “ Oh, I've already eaten dinner! " Then he stood up and continued to work. He had already forgotten the thing that he had invited the friend to dinner.