I've been thinking. With the slight implementation of books in the current build, an ability to copy them will eventually be necessary. In the event that a knowledgeable dwarf gets a mood they may compile that knowledge into a tome. This tome will then be usable to train subsequent dwarves in the skills its associated with--similar to how reading a book/slab with the information of life and death can make you a necromancer in adventure mode.
However, just one tome won't be enough to teach all your dwarves the desired skills; duplicates will be necessary. This is when scribes come into play. Scribes would heavily utilize reading, writing, and wordsmith skills. Dwarves assigned to scribe work can begin with simply duplicating books but can progress over time. Eventually a scribe can begin to compile different works into a single volume, add person knowledge and experience, and eventually write their own completely seperate books on the topic(s) (due to the dwarf in question getting increased skill from just simply working with the material).
Over time the fortress in question may become a great repository that can bring in further researchers, alchemist, magician, historians, etc. The fortress can become a time capsule that can be sealed in the event of social collapse fun to preserve the information for adventurers or future embarkers to discover.
Caravans can haul massive amounts of the texts across kingdoms spreading knowledge that can lead to greater cities, monolithic structures, techniques, equipment/weapons, artwork, crafts, etc that can give it a greater chance to successful defend and conquer.