Feudalism in Europe and Japan

"To William most glorious duke of the Aquitanians, bishop Fulbert the favor of his prayers. Asked to write something concerning of fealty, I have noted briefly for you on the authority of the books the things which follow. He who swears fealty to his lord ought always to have six things in memory; what is harmless, safe, honorable, useful, easy, practicable."

This passage describes__________________.