John of Salisbury in his Policraticus tells an experience from his own youth. He was studying Latin from a priest, using the Psalms as the texts for study. As it happened, however, his teacher was an adept in the divinatory art of crystal-gazing, and abused his trust by making John and a somewhat older pupil participate in these activities. The idea was to anoint the boys' fingernails with some sacred chrism so that images would appear reflected in the nails and would impart information. Alternatively, a polished basin might be used as the reflecting surface. After certain “preliminary magical rites” and the requisite anointing, the priest uttered names “which by the horror they inspired, seemed to me, child though I was, to belong to demons.” The other pupil declared that he saw “certain misty figures,” but John himself saw nothing of the sort and was thus ruled unqualified for this art. John goes on to say that almost all the people he knew who engaged in such practices were punished later in life with blindness and other afflictions. He knew only two exceptions, including the priest who had taught him Latin; both of these men repented and entered into religious life as monks or canons, and even they were punished somewhat for their offenses.