Against this Molina maintained that the human faculties having been elevated by what might be called prevenient Grace, so as to make them capable of producing a supernatural act, the act itself is performed by the will co-operating with the impulse given by God. Man is, therefore, free, and at the same time dependent upon God in the performance of every good act. He is free, because the human will may or may not co-operate with the divine assistance, and he is dependent upon God, because it is only by being elevated by prevenient Grace freely given by God that the human will is capable of co-operating in the production of a supernatural act. It follows, too, that the efficaciousness of Grace arises not from the Grace itself but from the free co-operation of the will, and that a Grace in itself truly sufficient might not be efficacious through the failure of the will to co-operate with it. The omniscience of God is safeguarded, because, according to Molina, God sees infallibly man's conduct by means of the /scientia media/ or knowledge of future conditional events (so called because it stands midway between the knowledge of possibles and the knowledge of actuals). That is to say He sees infallibly what man would do freely in all possible circumstances were he given this or that particular Grace, and acting upon this knowledge He predestines the just to glory /post praevisa merita/. The main difficulty urged against Molina was, that by conceding too much to human liberty he was but renewing in another form the errors of Pelagius; while the principal objection brought forward against the Dominicans was, that by conceding too much to Grace they were destroying human liberty, and approaching too closely to Calvin's teaching on Predestination. Needless to say, however much they differed on the points, both the followers of St. Thomas and the friends of Molina were at one in repudiating the doctrines of Calvin and Pelagius.