Once there was a fox. He was hungry. He went in search of food. He could not find any food. At last he reached a vineyard. Bunches of grapes were hanging. He wanted to get them.
His mouth began to water. The grapes were very high. He tried to get at the grapes. He jumped again and again. But all his efforts were useless. The grapes were too high for him to reach. He got tired. He was sure that he could not get the grapes. He gave up the attempt. He went away saying that the grapes were sour.
Moral: The grapes are sour if they are not within reach.