I'm opening the book
The book seems to give advice on sexuality authorized by the Church.
You decide to read a page at random, and the page you come across gives certain prohibitions.
+ No sexual relations on Sunday because it is a blessed day
+ Not on Saturday, in preparation for Sunday
+ Not on Wednesday or Thursday because they are days of mourning
+ Not on religious holidays
+ Not during the three 40-day periods of Lent
+ Not during menstruation and pregnancy