181. It has now also been granted me to observe several kinds of spirits, such as those who are delighted with measurements and the like, whose nature seems to be derived from the study of the geometrical sciences. Their imaginations, which were then exhibited to me, were engaged upon those studies, that they might relate all things in a wonderful manner to measurements, nor were those spirits evil, as they seemed to me. There was another kind of spirits who were boastful; nor were these very evil, etc. etc. Indeed, spirits are only affections, who affect man with a certain exquisite delight; if they are evil female spirits they are to be called sirens.