This effect is done with two books.
One has the title “Everything that women know about men”,
The other “Everything men know about women”.
When showing the first book, it is obvious that women know all about men.
But When the other book is shown, all pages are blank, only the page numbers are printed.
Apparently men do not know women well.
A viewer is asked to select and read (briefly) a page on the first book.
He (or she) must also remember the page number you selected.After a short trip to fantasy, the page inside the book disappears (the viewer can check it for yourself), your page is now blank.
In the other book, previously blank, the missing impression appears on the exact page that the viewer selected.
2 Books are supplied in Spanish