(Note: sometimes descriptive books are referred to as linking books as well, but strictly speaking, that usage is not correct, as there is a distinction between the two.)

Linking books, or korvakhtee, in the M/R/D/E world, were written by the D'ni using special materials (ink and paper among them), and a (presumably) standard format for the text, which would allow the user of the book to link to the place where it was written. A linking book works by creating a small tunnel of sorts to the between-universe link of the descriptive book (kormahn) for the destination Age. Thus, if the descriptive book were destroyed, all linking books written in that Age would stop working.

Though there is still some debate, it is generally considered impossible to link directly between places in the same Age; therefore, a linking book is not useful immediately after it is written; it must be taken out of the destination Age first.

There are a few good reasons for using primarily linking books rather than descriptive books to link:

  • Linking books are easier to produce than descriptive books. The consensus is that it is not necessary to have any knowledge of the descriptive book for an Age when writing a linking book to a place within it; thus, the standard formula suffices.
  • Linking books are smaller, and thus lighter, than descriptive books. The standard formula used for linking books does not include a description of the entire Age, as it is necessary to include when writing descriptive books; thus, linking books are more portable.
  • Linking books are less precious than descriptive books. If a descriptive book is lost or destroyed, essentially the entire link to the Age is lost. Linking books to the Age will no longer function, and even copying the words verbatim into a new descriptive book has an infinitesimal probability of linking to the same Age.
  • Linking books are more precise location-wise. The initial link to an Age (through a descriptive book) might link to nearly any place in the Age (though there are some general heuristics), whereas linking books always link to the exact spot in which they were written.

When linking away from your homeworld, one of the cardinal rules of thumb is to always bring along a linking book back to your previous location.

There is some debate regarding how any linking books could be created to the original D'ni homeworld, Garternay, as no descriptive book had been written for it. Some of the solutions proposed so far include:

  • There is a third type of book (name unknown), which acts like a linking book but does not require a descriptive book to exist. This raises the problem of why these books were not used more often; however, it is very possible that these books took even more work than descriptive books to write, and so would only have been used for Garternay, after which the practice was abandoned.
  • Time is circular, and there was in fact a descriptive book for Garternay.

Primary sources:

  • Colin Wilson's Gehn's Book problem, at <http://www.dur.ac.uk/~dph3cdw/gehn.html>
  • Colin Wilson's Mechanics of Linking, at <http://www.dur.ac.uk/~dph3cdw/linkmech.html>
  • The MYSTcommunity forums, at <http://www.mystcommunity.com/forum/>