says (De Civ. Dei xi, 13), if anyone subscribes, he does not agree
with those Manichean heretics who say that the devil's nature is evil
of itself. Since this opinion, however, is in contradiction with the
authority of Scripture--for it is said of the devil under the figure
of the prince of Babylon (Isa. 14:12): "How art thou fallen . . . O
Lucifer, who didst rise in the morning!" and it is said to the devil
in the person of the King of Tyre (Ezech. 28:13): "Thou wast in the
pleasures of the paradise of God,"--consequently, this opinion was
reasonably rejected by the masters as erroneous.

Hence others have said that the angels, in the first instant of their
creation, could have sinned, but did not. Yet this view also is
repudiated by some, because, when two operations follow one upon the
other, it seems impossible for each operation to terminate in the one
instant. Now it is clear that the angel's sin was an act subsequent to
his creation. But the term of the creative act is the angel's very
being, while the term of the sinful act is the being wicked. It seems,
then, an impossibility for the angel to have been wicked in the first
instant of his existence.

This argument, however, does not satisfy. For it holds good only in
such movements as are measured by time, and take place successively;
thus, if local movement follows a change, then the change and the
local movement cannot be terminated in the same instant. But if the
changes are instantaneous, then all at once and in the same instant
there can be a term to the first and the second change; thus in the
same instant in which the moon is lit up by the sun, the atmosphere
is lit up by the moon. Now, it is manifest that creation is
instantaneous; so also is the movement of free-will in the angels;
for, as has been already stated, they have no occasion for comparison
or discursive reasoning (Q. 58, A. 3). Consequently, there is nothing
to hinder the term of creation and of free-will from existing in the
same instant.

We must therefore reply that, on the contrary, it was impossible for
the angel to sin in the first instant by an inordinate act of
free-will. For although a thing can begin to act in the first instant
of its existence, nevertheless, that operation which begins with the
existence comes of the agent from which it drew its nature; just as
upward movement in fire comes of its productive cause. Therefore, if
there be anything which derives its nature from a