A person is born with certain spiritual strengths and a certain status of soul. Certain spiritual strengths are given and others are only potential. In order for G-d to be metiv, He has to influence a certain abundance which produces good. On the other hand, if G-d wants to bring suffering to the world He brings down an abundance of evil through the Satan. Our world is influenced by abundance which can either be for good or can come from evil, depending upon its objective.