Although I do not know the intricacies, it is surely not that difficult to explain I think. For starters, since that's how many things are with Japan having origins in China, look at chado and teaism as can be described by Okakura in "The book of tea". Teaism has its roots in taoism. Not surprisingly chadoa seems also to have its root in daoism. Now, tao might entail a few things but it is basically about simplicity, being there in the present moment, emptiness. Taking the approach by Zen is good way I find.
The thing I would not understand right away is why tea has a role in this, in both China and Japan. I mean, if you want to be just there why would one need to have tea ? Because eternity is long ?
Okakura's book is a very nice read. It is available in several editions, one with stylistic pictures, and one about to be published. The text is the same, written circa 1920. Your public library might have it.
Another one which I just found now and added to my list is "Cha Dao: The Way of Tea, Tea As a Way of Life" by Daoist meditation teacher Solala Towler.