[ryuurui]

Yeah, I think it is a classical Chinese four-verse.

One thing is certain, that his calligraphy is really good (and his bio says that he was a painter not a calligrapher), and I can see that his brushwork has solid foundations. It seems that that four-verse's style is based on works of 颜真卿 (Yán Zhēnqīng, 709–785). Calligraphy and ink-painting are sister arts, and they suplement each other. Usually both disciplines are studied in deapth, especially by more renowned artists. So, if that seal is authentic, this scroll (i presume it is a scroll) may be worth a bit.