An artwork of calligraphy

This calligraphy is a work of Ryokan, one of greatest poets in Edo era, 1603 to 1867. The letters were written in a very unique way and far from the ones that we can read today. So most of us cannot read these letters. If people who don't know Japanese letters see the work, then they may take it for Arabic characters.

A set of the letters seems to be not only a tool to pass on idea, feeling and information, but also a tool to express the beauty and feeling that can be expressed by the words. I feel as if the line and curve of this work express his pure mind, far from vanity, though I cannot totally understand what the work says. How do you feel, seeing this work?