Only a few years before The Pilgrim's Progress, Bunyan had written one of the most remarkable and powerful accounts of prolonged psychological anguish ever to have been published in English. This was his spiritual autobiography, Grace Abounding to the Chief of Sinners (1666), in which he recounts in vivid and harrowing detail his own experience of religious conversion and the psychological ordeal he had to go through before entering upon what would be his vocation as a preacher and writer. Grace Abounding has come to be regarded as a paradigmatic case history in the psychology of religious belief. It has been suggested that Bunyan was suffering from a variety of mental problems, including serious depression, and many attempts have been made to identify in medical or psychiatric terms what the causes of this may have been. Whether or not the evidence allows us to make specific diagnoses, it is certainly hard for a modern reader not to interpret Bunyan's ordeal as, in some sense, a psychological one. Bunyan emerged from his ordeal, however, and was able to transmute his own painful experiences into a richly imagined allegorical narrative. In its inward-turning, isolated and agonized preoccupation with his own experiences, Grace Abounding contrasts with the confident expansiveness of The Pilgrim's Progress and its range of characters. But the most important of the struggles and trials of the pilgrims continue to be inward and psychological ones. Bunyan's representation of how his pilgrims deal with these psychological problems is a large part of the continuing fascination and attractiveness of his work for modern readers.