When moonlight shines through a doorway ... Ma is a term to describe a uniquely Japanese concept of 'negative' or 'empty' space.
The character for Ma (間) is made from two separate ones: 門 (gate) and 日(sun)- originally, sun was moon (月).The two characters together describe the moment when moonlight shines through a hole or a doorway. One could say that this ideogram expresses both the objective and subjective aspect of space: that which can betouched (the actual doorframe) and that which can be sensed (the moon or sun shining through it). I, who cannot speak a word of Japanese, use the word Ma often and freely in this way. Whenever I have been working for too long without taking a break, for instance, I might say: 'I need some Ma'. Also, when laying the table for dinner when guests come round, I always make sure there is a little Ma surrounding each item on the table.
Thirty spokes meet in the hub, but the empty space between them is the essence of the wheel.
Pots are made of clay, but the empty space within is the essence of the pot.
Walls with windows and doors make the house, but the empty space within is the essence of the home.