The books containing the magical knowledge written by Merlin were in many volumes and all were in alphabetical order, so that you could easily find each thing.

The old Wizard, therefore, first searched under the word "Princess" . . .

Princess: Spells to lock a Princess in high brass walls, which cannot be broken down by any means, except with the music of a specific trumpet . . .

And many more such things. However, there was not a single word anywhere about how you could prevent a Princess from falling into a deep sleep if she had pricked her finger with the spindle of a wheel.