26. It is again well to consider that moral evil is an evil so great only because it is a source of physical evils, a source existing in one of the most powerful of creatures, who is also most capable of causing those evils. For an evil will is in its department what the evil principle of the Manichaeans would be in the universe; and reason, which is an image of the Divinity, provides for evil souls great means of causing much evil. One single Caligula, one Nero, has caused more evil than an earthquake. An evil man takes pleasure in causing suffering and destruction, and for that there are only too many opportunities. But God being inclined to produce as much good as possible, and having all the knowledge and all the power necessary for that, it is impossible that in him there be fault, or guilt, or sin; and when he permits sin, it is wisdom, it is virtue. 27. It is indeed beyond question that we must refrain from preventing the sin of others when we cannot prevent their sin without sinning ourselves. But someone will perhaps bring up the objection that it is God himself[139] who acts and who effects all that is real in the sin of the creature. This objection leads us to consider the _physical co-operation_ of God with the creature, after we have examined the _moral co-operation_, which was the more perplexing. Some have believed, with the celebrated Durand de Saint-Pourcain and Cardinal Aureolus, the famous Schoolman, that the co-operation of God with the creature (I mean the physical cooperation) is only general and mediate, and that God creates substances and gives them the force they need; and that thereafter he leaves them to themselves, and does naught but conserve them, without aiding them in their actions. This opinion has been refuted by the greater number of Scholastic theologians, and it appears that in the past it met with disapproval in the writings of Pelagius. Nevertheless a Capuchin named Louis Pereir of Dole, about the year 1630, wrote a book expressly to revive it, at least in relation to free actions. Some moderns incline thereto, and M. Bernier supports it in a little book on freedom and freewill. But one cannot say in relation to God what 'to conserve' is, without reverting to the general opinion. Also it must be taken into account that the action of God in conserving should have some reference to that which is conserved, according to what it is and to the state wherein it is; thus his action cannot be general or indeterminate. These generalities are abstractions not to be found in the truth of individual things, and the conservation of a man standing is different from the conservation of a man seated. This would not be so if conservation consisted only in the act of preventing and warding off some foreign cause which could destroy that which one wishes to conserve; as often happens when men conserve something. But apart from the fact that we are obliged ourselves sometimes to maintain that which we conserve, we must