This fascinating collection of essays takes us on a journey into the heart of Chabad Chasidism — its intellectual roots, social history and relationship to post-modernity. The impression is of a movement living in two realms: the medieval and modern, insular and outward looking, rational and mystical. All this is reflected in the theology of its Rebbes.

In 1752, the Ba’al Shem Tov (Chasidism’s founder) wrote a letter to his brother-in-law, Rabbi Gershon of Kuty, in which he describes a mystical “ascent of the soul”. On entering the heavenly palace, the Ba’al Shem Tov happens upon the Messiah and asks him when he will come. The Messiah answers, “When your teaching is… revealed to the world, and your wellsprings gush outwards”.

Those words encapsulate the Chabad ideal as it developed. The meaning was clear: the Messiah would come when Chabad Chasidism spread abroad. And so Chabad has become a global movement, powered by dedicated emissaries fuelled by a belief in the sacredness of their task and holy potential of every individual, whether Jew or Gentile.

Dr Loewenthal masterfully links these ideals and the activism they inspire to their theological roots. In Tanya, the first Lubavitcher Rebbe, Rabbi Shneur Zalman, promotes a spirituality which darts between the rational and mystical; faith is drawn into reason but at the same time bidden to overcome it.

This same movement between the worldly and otherworldly, the secular and traditional, comes to feature in all aspects of Chabad life. Graveside veneration of the Rebbe and mystical particularism mix with the practical and forward-looking. Loewenthal’s personal background reflects this dichotomy. He is a UCL academic, immersed in the study of history, ideas, language, and a Chabad Chasid. His story is central to his task, which is not only to give an account of Chabad, but to explore the postmodern potential of faith more broadly.