Thousands years ago, according to an Ancient Chinese legend, Buddha decided to choose animals as the signs of 12 year cycle. He summoned all the animals to be present at a meeting next morning and he would secretly select the first arrival 12 animals to be the signs of a year respectively. The rat and cat, who were good friends, agreed to wake each other up. Next morning, Rat, who woke up first, broke his promise and left cat asleep as he quietly left for the meeting alone. Buddha selected the first arrival 12 animals as the signs for the years. They came in this order: the rat, ox, tiger, rabbit, dragon, snake, horse, goat, monkey, rooster, dog, and the pig. By the time cat arrived everyone has been celebrating their good fortune and that is why there is no cat in the zodiac. Needless to say, Cat and Rat became enemies from then on.
Another version of story to tell why rat is the first of the 12 Zodiac:
Regarding Chinese legend, the twelve animals quarreled one day as to who was to head the cycle of years. The gods were asked to decide and they held a contest: whoever was to reach the opposite bank of the river would be first, and the rest of the animals would receive their years according to their priorities.
All the twelve animals gathered at the river bank and jumped in. Unknown to the ox, the rat had jumped upon his back. As the ox was about to jump ashore, the rat jumped off the ox's back, and won the race. The pig, who was very lazy, ended up last. That is why the rat is the first year of the zodiac cycle, the ox second, and the pig last.
The Chinese Zodiac is based on a twelve year cycle --- each year being represented by an animal that imparts distinct characteristics to its year. Many Chinese believe that the year of a person's birth is the primary factor in determining that person's personality traits, physical and mental attributes and degree of success and happiness throughout his lifetime.
Do you want to discover the secrecy of your fate deduced from Chinese theory of fate? Just select the date you were born and begin your fancy explomouseion. Don't take it serious whatever it's good or bad. Just for fun! Actually, this is just an alternative way to say how old you are.