aid their progress.... Let us compare the force which the
current exercises over the vessels and what it communicates to them, with
the action of God, who produces and preserves whatever is positive in the
creature, and imparts to them perfection, being, and force; let us
compare, I say, the inertia of matter with the natural imperfection of
creatures, and the slowness of the more heavily laden vessel with the
defect which is found in the qualities and in the actions of the creature,
and we shall perceive that there is nothing so just as this comparison.
The current is the cause of the movement of the vessel, but not of its
retardation; God is the cause of the perfection in the nature and the
actions of the creature, but the limitation of the receptivity of the
creature is the cause of the defect in its actions. Thus the Platonists,
St. Augustine, and the schoolmen, have reason to say that God is the
material cause of evil, which consists in what is positive, and not the
formal cause of it, which consists in privation, as we can say that the
current is the material cause of the retardation, without being its formal
cause; that is to say, is the cause of the swiftness of the vessel,
without being the cause of the bounds of that swiftness. God is as little
the cause of sin, as the current of the river is the cause of the
retardation of the vessel."(73) Or as Leibnitz elsewhere says, God is the
author of all that is positive in our volitions, and the pravity of them
arises from the necessary imperfection of the creature.

We have many objections to this mode of explaining the origin of moral
evil, some few of which we shall proceed to state. 1. It is a hopeless
attempt to illustrate the processes of the mind by the analogies of
matter. All such illustrations are better adapted to darken and confound
the subject, than to throw light upon it. If we would know anything about
the nature of moral evil, or its origin, we must study the subject in the
light of consciousness, and in the light of consciousness alone. Dugald
Stewart has conferred on Descartes the proud distinction of having been
the first philosopher to teach the true method according to which the
science of mind should be studied. "He laid it down as a first principle,"
says Stewart, "that nothing comprehensible by the imagination can be at
all subservient to the knowledge of mind; and that the sensible images
involved in all our common forms of speaking concerning i