A well-written and important article:
THE SPIRITUAL TEACHER IN THERAVĀDA BUDDHISM: INNER MOTIVATIONS AND FOUNDATIONS OF MINDFULNESS
This study is divided into three parts: a) first of all I shall consider, with particular reference to the Lohiccasutta , some of the psychological aspects that distinguish the “blameworthy teacher” and, as a result, obtain some criteria of the qualities of the proper teacher; b) I shall then turn my attention to the time when the Buddha decides toreveal his message, to the time when, to all intents and purposes, he becomes a teacher; c) I shall conclude with a careful examination of the ways in which the teacher must carry out his duties, paying particular attention to the Saláyatanavibhangasutta, in which we come across a threefold satipatthána that seems to be especially meant for the teacher. The practice expressed in the threefold satipatthána is, together with the qualities that characterize the proper spiritual guide, the very core of the relationship between teacher and disciple. The three parts of the study are decidedly interconnected, sincethe description of the blameworthy teacher contains the coordinate terms to describe the figure of the good teacher and vice versa.
http://www.academia.edu/3714167/The_spi ... indfulness