Last night someone asked about the Fukanzazengi which we recite on Thursday evenings... Here's what I found...
"Dogen Zenji was the 13th century founder of Soto Zen in Japan, and we trace our practice here back through Dogen. When he returned to Japan after practicing in China, he wrote the "Fukanzazengi." This two page text was Dogen’s main meditation manual, which he continued working on for about twenty-six years until near the end of his life."