This is a case with a long chronic evolution, which shows the narrow relations which may exist between dreams and delusions. Whether dreaming during sleep, or apparently at times dreaming when awake, the patient presented persistent delusions which were grafted on or sprang from the dreams, and occasionally led to acts. O. L— was aged 49 when he came under the authors' care, having been in the post office for twenty-four years; he complained of pains in the lower limbs, which exaggerated a natural limp (due to former injuries), and pains in the head, which he referred to visions he had recently experienced. The patient had written a long account of these hallucinations, which revealed two dominant ideas: (1) that the patient was God's elect, and (2) that he was persecuted. To explain them he referred to certain episodes which had occurred far back in his life, and the visions seemed to be of two kinds: (a) representations of his ordinary life; (b) supernatural. As regards these supernatural visions, a few of these were extra-terrestrial (referring to the heavens, to the sun, etc.), but most (a large number altogether) were terrestrial (a rainbow descending about the patient's head, beholding Christ on the Cross appearing on a newspaper he was reading, a star falling and the moon stretching out to catch it, etc.). Hallucinations of hearing occasionally accompanied the last-mentioned hallucination of vision. The ideas of persecution arose in his mind at the time of appearance of these visions; they mostly referred to his thoughts being read. The various hallucinations appear to begin in dreams, during which he is authorised to divulge them, etc.