FROM the end of the thirteenth to the beginning of the fifteenth century may be called the golden age of mystical literature in the vernacular. In Germany, we find Mechthild of Magdeburg (d. 1277), Meister Eckhart (d. 1327), Johannes Tauler (d. 1361), and Heinrich Suso (d. 1365); in Flanders, Jan Ruysbroek (d. 1381); in Italy, Dante Alighieri himself (d. 1321), Jacopone da Todi (d. 1306), St. Catherine of Siena (d. 1380), and many lesser writers who...