In a word, spirit. Material all by itself has no impetus to move.
Material can cause other material to move in cases of “event causation”, but to think sequences of this can be past-eternal is naive, as it relies on infinite regress (which is impossible). The other type of causation — agent causation — makes more sense as an action of “The First Mover”. If we consider the two candidates for “The First Mover”, or “The Prime Reality”: material or spirit, the latter is the hands-down more sensible inference, in my opinion.