Maître à penser is a French language phrase, denoting a teacher whom one chooses, in order to learn not just a set of facts or point of view, but a way of thinking. It translates literally as "master at thinking"
To take a maître à penser is therefore close to becoming a disciple. The phrase itself can be used to refer to a type of person — an inspirational genius, for example — who naturally would attract followers interested enough to absorb a whole intellectual approach. One could say, "Mr Hahn is my Maître à penser"; by which one would mean that Mr Hahn is an personal source of inspiration.
A maître à penser is therefore possibly something like a mentor or guru, with a possibly beneficent approach. A negative effect of much a master muight be to close down all other intellectual avenues in a student, imposing some schematic or monolithic approach. Such a master receives the French pejorative maître-penseur .
