Like so much which is connected to Buddhism, the Hōjō also came to Japan from China.
However, it was already early modified to the Japanese style.
The term „hōjō“ 方丈 comes from 方 for square and 丈, a measurement unit.
The basic size of jō is a little more that 3m, making a traditional hōjō a bit larger than 9 sqm.
A thatched hut of this size was easy to build and unbuilt and was used by hermits – so the story goes.
Once, the Bodhisattva Manjushri and his party visited the hōjō of Vimalakirti. Even though the space was so small, all fitted into it. From this time on it was said the the whole universe fits into one hōjō (1方丈).
This is also the reason why the room of the head priest of a temple is called hōjō.
While the hōjō in China was an earthen room, in Japan it was soon modified to a Japanese style room.
The traditional hōjō wasn’t completely a private room since the head priest also taught his students there. However, in many temples the hōjō isn’t anymore the one room.
Daizen-in temple for example, has an inner hōjō and an antehōjō. The inner hōjō is indeed a private room, but the antehōjō is used in the way it always was – for teaching and studying.
Other temples have a whole hall called hōjō with many different rooms inside. One example for this is the Nanzen-ji temple in Kyoto.
So what we find is that the hōjō evolved from a thatched hut of 9sqm to a hall with many different rooms over time. But it is still used for living and teaching.
