Perhaps more than any other person in the twentieth century,
Though she is best known for her books and articles on mysticism,
also wrote short stories, novels, poetry, devotional works, book reviews, and biographies. In addition, she edited and supplied prefatory pieces to several religious texts, and translated medieval folk tales.
was responsible for fanning interest in and shaping the study of mysticism. Most of her works draw on her extensive knowledge of mystical texts from various times and places—knowledge that she uses to rescue the practice of mysticism from its antique, occult associations and argue for its applicability to modern life. In about four decades, she issued thirty-nine full-length volumes and over 350 shorter pieces.