THIRD ARTICLE [I, Q. 111, Art. 3]

Whether an Angel Can Change Man's Imagination?

Objection 1: It would seem that an angel cannot change man's

imagination. For the phantasy, as is said _De Anima_ iii, is "a motion

caused by the sense in act." But if this motion were caused by an

angel, it would not be caused by the sense in act. Therefore it is

contrary to the nature of the phantasy, which is the act of the

imaginative faculty, to be changed by an angel.

Obj. 2: Further, since the forms in the imagination are spiritual,

they are nobler than the forms existing in sensible matter. But an

angel cannot impress forms upon sensible matter (Q. 110, A. 2).

Therefore he cannot impress forms on the imagination, and so he

cannot change it.

Obj. 3: Further, Augustine says (Gen. ad lit. xii, 12): "One spirit

by intermingling with another can communicate his knowledge to the

other spirit by these images, so that the latter either understands

it himself, or accepts it as understood by the other." But it does

not seem that an angel can be mingled with the human imagination, nor

that the imagination can receive the knowledge of an angel. Therefore

it seems that an angel cannot change the imagination.

Obj. 4: Further, in the imaginative vision man cleaves to the

similitudes of the things as to the things themselves. But in this

there is deception. So as a good angel cannot be the cause of

deception, it seems that he cannot cause the imaginative vision, by

changing the imagination.

_On the contrary,_ Those things which are seen in dreams are seen by

imaginative vision. But the angels reveal things in dreams, as

appears from Matt. 1:20; 2:13, 19 in regard to the angel who appeared

to Joseph in dreams. Therefore an angel can move the imagination.

_I answer that,_ Both a good and a bad angel by their own natural

power can move the human imagination. This may be explained as

follows. For it was said above (Q. 110, A. 3), that corporeal nature

obeys the angel as regards local movement, so that whatever can be

caused by the local movement of bodies is subject to the natural

power of the angels. Now it is manifest that imaginative apparitions

are sometimes caused in us by the local movement of animal spirits

and humors. Hence Aristotle says (De Somn. et Vigil.) [*De Insomniis

iii], when assigning the cause of visions in dreams, that "when an

animal sleeps, the blood descends in abundance to the sensitive

principle, and movements descend with it," that is, the impressions

left from the movements are preserved in the animal spirits, "and

move the sensitive principle"; so that a certain appearance ensues,

as if the sensitive principle were being then changed by the external

objects themselves. Indeed, the commotion of the spirits and humors

may be so great that such appearances may even occur to those who are

awake, as is seen in mad people, and the like. So, as this happens by

a natural disturbance of the humors, and sometimes also by the will

of man who voluntarily imagines what he previously experienced, so

also the same may be done by the power of a good or a bad angel,

sometimes with alienation from the bodily senses, sometimes without

such alienation.

Reply Obj. 1: The first principle of the imagination is from the

sense in act. For we cannot imagine what we have never perceived by

the senses, either wholly or partly; as a man born blind cannot

imagine color. Sometimes, however, the imagination is informed in

such a way that the act of the imaginative movement arises from the

impressions preserved within.

Reply Obj. 2: An angel changes the imagination, not indeed by the

impression of an imaginative form in no way previously received from

the senses (for he cannot make a man born blind imagine color), but

by local movement of the spirits and humors, as above explained.

Reply Obj. 3: The commingling of the angelic spirit with the human

imagination is not a mingling of essences, but by reason of an effect

which he produces in the imagination in the way above stated; so that

he shows man what he [the angel] knows, but not in the way he knows.

Reply Obj. 4: An angel causing an imaginative vision, sometimes

enlightens the intellect at the same time, so that it knows what

these images signify; and then there is no deception. But sometimes

by the angelic operation the similitudes of things only appear in the

imagination; but neither then is deception caused by the angel, but

by the defect in the intellect to whom such things appear. Thus

neither was Christ a cause of deception when He spoke many things to

the people in parables, which He did not explain to them.

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Summa Theologica, Part I (Prima Pars) From the Complete American Edition · 第 678 / 722 题