FIFTH ARTICLE [I, Q. 79, Art. 5]

Whether the Active Intellect Is One in All?

Objection 1: It would seem that there is one active intellect in all.

For what is separate from the body is not multiplied according to the

number of bodies. But the active intellect is "separate," as the

Philosopher says (De Anima iii, 5). Therefore it is not multiplied in

the many human bodies, but is one for all men.

Obj. 2: Further, the active intellect is the cause of the universal,

which is one in many. But that which is the cause of unity is still

more itself one. Therefore the active intellect is the same in all.

Obj. 3: Further, all men agree in the first intellectual concepts.

But to these they assent by the active intellect. Therefore all

agree in one active intellect.

_On the contrary,_ The Philosopher says (De Anima iii, 5) that the

active intellect is as a light. But light is not the same in the

various things enlightened. Therefore the same active intellect is

not in various men.

_I answer that,_ The truth about this question depends on what we

have already said (A. 4). For if the active intellect were not

something belonging to the soul, but were some separate substance,

there would be one active intellect for all men. And this is what

they mean who hold that there is one active intellect for all. But if

the active intellect is something belonging to the soul, as one of

its powers, we are bound to say that there are as many active

intellects as there are souls, which are multiplied according to the

number of men, as we have said above (Q. 76, A. 2). For it is

impossible that one same power belong to various substances.

Reply Obj. 1: The Philosopher proves that the active intellect is

separate, by the fact that the passive intellect is separate:

because, as he says (De Anima iii, 5), "the agent is more noble than

the patient." Now the passive intellect is said to be separate,

because it is not the act of any corporeal organ. And in the same

sense the active intellect is also called "separate"; but not as a

separate substance.

Reply Obj. 2: The active intellect is the cause of the universal, by

abstracting it from matter. But for this purpose it need not be the

same intellect in all intelligent beings; but it must be one in its

relationship to all those things from which it abstracts the

universal, with respect to which things the universal is one. And

this befits the active intellect inasmuch as it is immaterial.

Reply Obj. 3: All things which are of one species enjoy in common the

action which accompanies the nature of the species, and consequently

the power which is the principle of such action; but not so as that

power be identical in all. Now to know the first intelligible

principles is the action belonging to the human species. Wherefore

all men enjoy in common the power which is the principle of this

action: and this power is the active intellect. But there is no need

for it to be identical in all. Yet it must be derived by all from one

principle. And thus the possession by all men in common of the first

principles proves the unity of the separate intellect, which Plato

compares to the sun; but not the unity of the active intellect, which

Aristotle compares to light.

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Summa Theologica, Part I (Prima Pars) From the Complete American Edition · 第 491 / 722 题