Lu-Tze is a history monk who first appeared IIRC in Small Gods. In Thief of Time, he gets co-opted into teaching a most unusual acolyte who has a singular characteristic I won't spoil for you. Lu-Tze is a bit of a caricature of stereotypical eastern martial arts masters, BTW. His acolyte, of course, doesn't quite understand Lu-Tze's approach and often asks questions. But then, when asked what he would like for breakfast, Lu-Tze would tend to answer with "Ah. One of the difficult questions". :-) Especially after a few minutes of meta-physics discussion.
Wade.