Grimoires (called Principiae by Technocrats) are Wonders (traditionally books, but most Technomancers prefer CD-ROMs or even diskettes) that contain magical formulae. They can teach Rotes and magical theory and even raise their Arete, provided the reader is compatible to their paradigm. Each grimoire reflects its creator and his style of magic.
In order to use a grimoire, the reader has to understand the language (part of the reason why most mages learn several languages). Accessing the knowledge of a grimoire requires the conscious act of reading, simply watching of the text in a movie does not work. Also, the time spent to read and comprehend the messages delivered by a grimoire is usually very long, as the reader follows the way of enlightenment of the writer. By fully comprehending a grimoire (which can span weeks, or even months), a mage can raise his Arete without a Seeking. The best way to utilize a grimoire, however is to practice the written thoughts. Some grimoires demand that the reader has to take specific body postures in order to read and understand the text, while others demand knowledge in special areas, like Cosmology, and they are almost universally infamous for making sudden intuitive leaps of logic that the texts are very difficult to understand: a reader with less cosmic comprehension of the subject than the writer had at the time of the writing will find it literally hard to comprehend. At least at first...
The most powerful grimoires are called primers and have the capability to Awaken a Sleeper, given that his Avatar is not too dormant or damaged. The most prominent primer is the Kitab Al-Alacir, which is still used to introduce Sleepers into the Sons of Ether.
In order to create a grimoire, the mage most provide all materials and skills needed to create the document. The ritual itself is time-consuming, allowing the mage only one pause per week to eat and drink. The whole process becomes much more difficult if the mage has problems expressing himself and needs magic to get the job done. In the end, the mage sacrifices a permanent point of Willpower and imbues it into the grimoire, preserving a part of himself in the pages like a fly in amber. As grimoires are still vulnerable to the ravages of time, most mages make sure to use only the highest quality of materials. Furthermore, a primer demands that the mage imbues a small part of his own Avatar in the text.