ANYONE can indeed cast ritual magic, provided they have the proper library and time to write up a ritual schema.  (plus the training in the spellcraft skill to do so)<br/><br/>The Rekkenmark archives are a mortal circle magical library (spell levels 0 to 3rd), although the sealed sections (off limits to all the party members, but within reach of Saithe and the school Demon) contain Giant circle magic.  (spell levels 4-6)   You can pretty much assume that the mortal circle sections of the school contain every spell in the spell compendium in the sorcerer/wizard, cleric, and assassain spell lists, while the giant circle section contains all the spells from the necromancy, conjuration, abjuration, evocation, and universal schools on those lists.