Michiko taught me this and I think the meaning is something like to practice swimming on a tatami mat is useless. Sure you can practice all you want, possibly different stokes and movements, but if your not actually in a body of water it doesn’t really benefit you. I have been in a lot of pain from stress and was trying to relax my body and mind through meditation. I picked up a book on Zazen meditation that I had purchased a long time ago and began to read it again. I felt like “tatami no ue no suiren” meaning that I was reading it and interepting the words, but wasn’t actually connecting with the real source of its meaning. I do however remember when I was in Kyoto at the Ryoanji Otera and felt a place and presence of where meditation might be useful. I hope to continue my pursuit of meditation and hopefully I will come across people along the way that can help guide me with useful ways to practice it versus sitting at home reading a book on how to practice Zazen.