Orlon Window

Do you know what an Orlon Window is, Angel? It's a fascinating little spell. It allows warlocks such as myself to see the past as it once was.
―Cyvus Vail[src]

An Orlon Window created a vessel which served as a window for the spell-caster to see the past as it once was (prior to any alterations). If the vessel was broken near any individual whose mind had been altered in any way, the memories that were altered or removed returned, adding to any new memories that may have been created to replace the former.