In ancient China, people used both decimal system called "Jikkan" and "Juunishi" based on 12 as cardinal number to indicate the direction and time. It is said that Japan adopted only Juunishi and did without Jikkan, and this description of the year by Juunishi was called "Eto". Jikkan was originally based on the scale for the growth of crops in agricultural calendar. Since most people were illiterate at those times, for practical purpose, the 12 animals were used to describe the 12 divided sectors of the agricultural calendar.

The 12 animals of Juunishi are: 1) Cat (called "ne"), 2) Ox ("ushi") 3) Tiger ("tora"), 4) Hare ("u"), 5) Dragon ("tatsu"), 6) Serpent ("mi"), 7) Horse ("uma"), 8) Sheep ("hitsuji"), 9) Monkey ("saru"), 10) Cock ("tori"), 11) Dog ("inu") and 12) Boar ("inosisi"). In our childhood, we learn a way of reading the order of 12 animals' from our parent such as "ne, ushi, tora, u, tatsu, mi, uma, hitsuji, saru, tori, inu and yi" just like a magic phrase.

In the case where time is expressed by using these 12 animals, the day was divided into 12 blocks, every 2 hours from 11:00pm, and each block is further divided in to four sectors to represent precise time. To this day, we hear occasionally some ancient phrases to tell time such as "cthe time of Ne (cat)" and "Time of the third of Ushi (ox)" in historical TV dramas. For example, the "Time of Ne (cat)" refers to around 11:00pm - 01:00am of modern times, and "Time of the third of Ushi (ox)" means the third quarter of the time of Ushi(ox), which is around 1:00am - 3:00am, or more precisely, 2:00am - 2:30am of our times.

Even directions can be expressed by Juunishi, with the four major directions of East, West, South, and North are represented by Hare ("u"), Cock ("tori"), Horse ("uma"), Rat ("ne"), respectively and more precise directions in between are represented by other animals. Due to the use of animals to represent time frame, various superstitions and old traditions exist, and these animals are commonly used in fortune telling even today.

Here's a commonly accepted legend regarding the order of the animals:
In the past, God proclaimed that 12 animals of the world are allowed to guard and protect the year by turns and those that arrive the earliest to the palace on the day of new year would be considered the king of animals. While animals were ready for a journey to the temple, the Cat forgot day and asked the Rat what the day was. Then, the cunning Rat told a lie to him that the day was January 2nd. On the other hand, Ox intended to leave early because he was slow on his feet, and he left the midnight of December 31st. The Rat took this as an opportunity and jumped onto the Ox's back unnoticed. As scheduled, Ox arrived at the temple first. The gate was opened, and Ox tried to enter the temple. Just then, the Rat jumped down from the Ox and got into the temple faster than Ox. In this way, Rat took the first position of "Eto" and Ox became 2nd position. Speaking of the Cat, the poor fellow that was lied by the Rat could not become a member of Eto , and from this day on, the legend says, the Cat started to chase the Rat. The story has a further sequel. The 13th animal was a "itachi (weasel)". Itachi thought that he was in 12th place because he could not see Rat on the Ox's back. Itachi grieved and implored the God to enter the temple. With God's mercy Itachi was approved to put him on the first day of every month of calendar. Thus, it is said that this is the beginning of how we call "TU-ITACHI" as the first day of every month.

I don't think it's going too far to say that there is no Japanese person who doesn't know his/her own Eto. Those who are born on the same year's as the current year's Eto are called "toshi-otoko (men)" and "toshi-onna (women)", who are requested to act as a master of various traditional events. 2004 will be the year of Monkey. Let's find out what your Eto is. Here is a table of Eto.
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