Casting From Text
In ArM5, magi cannot cast spells directly from books. Books of spells are actually Laboratory Texts, and contain instructions for inventing the spells, not for casting them.
The supplement Covenants did add the possibility of casting spells from a Casting Tablet, however. A casting tablet allows a magus to cast a spell, although not to learn or invent it.
Casting From Text in Previous Editions
In ArM3 and ArM4, covenants' spell books were called grimoires and magi could cast formulaic spells they didn't know by reading directly from a grimoire. This was risky, entailing extra botch dice. In ArM1 and ArM2 there is no mention of casting spells from text, you would have to learn or invent them in order to cast them.
See Also
- Casting Tablet, the ArM5 equivalent to casting from a text