Bernhard Pick 
The Cabala 

This is a short monograph on the Kabbalah, written from a purely academic and somewhat critical point of view. Pick traces the origins and background of the Kabbalah to Jewish scholars of mediaeval Spain. He does not attribute any deeper roots to it historically, nor does he examine the roots of Jewish mysticism except for a brief mention of the Merkabah. If you are looking for an introduction to the subject written by an advocate of the Kabbalah, it might be better to start with some other books on the subject. But if you need a starting point for further academic study, this is a good place to begin.