The idea is attributed to Louis de la Forge (1632-1666) in his Treatise on the Spirit of Man (1665), but the chief occasionalist was Nicolas Malebranche (1638-1715). Also see: psychophysical-parallelism.php and pre-established harmony.
Occasionalism says that there is only one true cause, God, who causes what seem to be effects to appear on the occasions when what seem to be causes appear. If I strike a match, God will cause the match to light; the striking being called an occasional cause of the lighting.
The theory arose largely because of difficulties experienced by Rene Descartes (1596-1650) in saying how mind and body -which on his dualist view he treated as totally different substances - could interact causally with each other. The theory was therefore primarily applied to mind/body interactions, but was extended more widely in so far as it was felt that matter was passive and could not itself contain powers or forces.
N Malebranche, Dialogues on Metaphysics and on Religion (1688; translated 1923), 7th Dialogue