Louis-Claude de Saint-Martin was born on 18 January 1743 in Amboise, France, into a noble but not wealthy family, and briefly pursued a legal and then a military career before turning decisively toward philosophy and mysticism in his mid twenties. Around 1768 he was initiated into Martinez de Pasqually's Order of the Elus Cohen, a theurgic Masonic rite built around elaborate ceremonial operations meant to help the initiate reintegrate with the divine, and for several years he served as Pasqually's secretary, absorbing the order's theology closely.
Over time Saint-Martin grew dissatisfied with the elaborate ceremonial apparatus of Cohen theurgy, coming to believe that the reintegration Pasqually's rituals sought could be reached more directly through inward contemplation and moral discipline alone, without external ritual machinery. He drifted away from active participation in the order, though he never formally renounced its teaching, and spent the following decades developing and writing his own increasingly interior mystical philosophy, corresponding widely with other European mystics, Jean-Baptiste Willermoz among them, and becoming known by the title his readers gave him, the Unknown Philosopher, after the pseudonym under which his first book appeared.