Concept of the Tea ceremony is to honor the guest.
You need to clear your mind and think nothing when making a cup of matcha tea for the guest.
There is popular Japanese old saying “茶禅一味/ “cha zen ichimi”
It means that chanoyu and Zen are of the same flavor. Indeed, chanoyu and Zen have maintained a close relationship from very outset.
Matcha was brought to Japan by the monk Eisai who studied Zen in Song dynasty China. (p91)
Tea ceremony is the most common phrase to describe “the way of tea” Chanoyu.
Chanoyu’s four principles of Wa-Kei-Sei-Jaku (harmony, respect, purity and tranquility) represent an ideal state that should realized through Zen. All grand tea masers in the Sen families undergo extensive Zen training. (p91)
The Chines characters to write Mushin are 無(nothing) and 心(heart/mind).Looking it from a Western prospective mushin is what I refer to as “being in the groove.” It is a state of mind where one is totally into what they are doing without any physical and mental distractions. In other words, it is the natural act of doing something without having to consciously think about it. It is something we have all experienced at one time or another in our own mundane endeavors