s his celebrated ontological proof. God is that being
than whom none greater can be conceived. Now, if that than which nothing
greater can be conceived existed only in the intellect, it would not be
the absolutely greatest, for we could add to it existence in reality. It
follows, then, that the being than whom nothing greater can be
conceived, i.e. God, necessarily has real existence. This reasoning, in
which Anselm partially anticipated the Cartesian philosophers, has
rarely seemed satisfactory. It was opposed at the time by the monk
Gaunilo, in his _Liber pro Insipiente_, on the ground that we cannot
pass from idea to reality. The same criticism is made by several of the
later schoolmen, among others by Aquinas, and is in substance what Kant
advances against all ontological proof. Anselm replied to the objections
of Gaunilo in his _Liber Apologeticus_. The existence of God being thus
held proved, he proceeds to state the rational grounds of the Christian
doctrines of creation and of the Trinity. With reference to this last,
he says we cannot know God from himself, but only after the analogy of
his creatures; and the special analogy used is the self-consciousness of
man, its peculiar double nature, with the necessary elements, memory and
intelligence, representing the relation of the Father to the Son. The
mutual love of these two, proceeding from the relation they hold to one
another, symbolizes the Holy Spirit. The further theological doctrines
of man, original sin, free will, are developed, partly in the
_Monologion_, partly in other mixed treatises. Finally, in his greatest
work, _Cur Deus homo_, he undertakes to make plain, even to infidels,
the rational necessity of the Christian mystery of the atonement. The
theory rests on three positions: that satisfaction is necessary on
account of God's honour and justice; that such satisfaction can be given
only by the peculiar personality of the God-man; that such satisfaction
is really given by the voluntary death of this infinitely valuable
person. The demonstration is, in brief, this. All the actions of men are
due to the furtherance of God's glory; if, then, there be sin, i.e. if
God's honour be wounded, man of himself can give no satisfaction. But
the justice of God demands satisfaction; and as an insult to infinite
honour is in itself infinite, the satisfaction must be infinite, i.e. it
must outweigh all that is not God. Such a penalty can only be paid by
God himself,