THE Days and Hours have already been treated of, in general, in the First Book. It is now necessary to notice in particular at what hour accomplishment and perfection should be given to the Arts, all things necessary having been previously prepared. Should it then happen that thou hast undertaken any secret operation for conversing with or conjuring Spirits, in which the day and the hour are not marked, thou shalt put it in execution on the days and hours of Mercury, at the sixteenth or…