The Master requires a Source of Magic to cast Magic spells. Each spell consumes one source. Sources can be found in Sim Mode in ActRaiser. The Origin of Magic is an item found in Act Mode that adds another source, but only for that Act. Basically, a Source of Magic (found in Sim Mode) is a permanent addition to the Master's stock and will replenish itself for every Act. An Origin of Magic, like the 1up, is only good for that one Act.