None could interpret the text, until one of them, Iohé Grevis, suggested that they should ask the Lord for understanding. The Angel of the Lord appeared to him and extracted a promise that he would keep the text hidden from the unworthy and the wicked, after which he was able to read it plainly. Iohé Grevis then placed a spell on the book that the unworthy, the unwise or those who did not fear God would not attain the desired effect from any of the workings contained in the book.