Long ago, in China, the Jade Emperor decided there should be a way of measuring time. On his birthday he told the animals that there was to be a swimming race. The first twelve animals across the fast flowing river would be the winners and they would each have a year of the zodiac named after them.
All the animals lined up along the river bank. The rat and the cat, who were good friends, were worried because they were poor swimmers. Being clever they asked the strong ox if he would carry them across the river.