FOURTH ARTICLE [I, Q. 85, Art. 4]

Whether We Can Understand Many Things at the Same Time?

Objection 1: It would seem that we can understand many things at the

same time. For intellect is above time, whereas the succession of

before and after belongs to time. Therefore the intellect does not

understand different things in succession, but at the same time.

Obj. 2: Further, there is nothing to prevent different forms not

opposed to each other from actually being in the same subject, as,

for instance, color and smell are in the apple. But intelligible

species are not opposed to each other. Therefore there is nothing to

prevent the same intellect being in act as regards different

intelligible species, and thus it can understand many things at the

same time.

Obj. 3: Further, the intellect understands a whole at the same time,

such as a man or a house. But a whole contains many parts. Therefore

the intellect understands many things at the same time.

Obj. 4: Further, we cannot know the difference between two things

unless we know both at the same time (De Anima iii, 2), and the same

is to be said of any other comparison. But our intellect knows the

difference and comparison between one thing and another. Therefore

it knows many things at the same time.

_On the contrary,_ It is said (Topic. ii, 10) that "understanding is

of one thing only, knowledge is of many."

_I answer that,_ The intellect can, indeed, understand many things

as one, but not as many: that is to say by _one_ but not by _many_

intelligible species. For the mode of every action follows the form

which is the principle of that action. Therefore whatever things the

intellect can understand under one species, it can understand at the

same time: hence it is that God sees all things at the same time,

because He sees all in one, that is, in His Essence. But whatever

things the intellect understands under different species, it does

not understand at the same time. The reason of this is that it is

impossible for one and the same subject to be perfected at the same

time by many forms of one genus and diverse species, just as it is

impossible for one and the same body at the same time to have

different colors or different shapes. Now all intelligible species

belong to one genus, because they are the perfections of one

intellectual faculty: although the things which the species represent

belong to different genera. Therefore it is impossible for one and

the same intellect to be perfected at the same time by different

intelligible species so as actually to understand different things.

Reply Obj. 1: The intellect is above that time, which is the measure

of the movement of corporeal things. But the multitude itself of

intelligible species causes a certain vicissitude of intelligible

operations, according as one operation succeeds another. And this

vicissitude is called time by Augustine, who says (Gen. ad lit. viii,

20, 22), that "God moves the spiritual creature through time."

Reply Obj. 2: Not only is it impossible for opposite forms to exist

at the same time in the same subject, but neither can any forms

belonging to the same genus, although they be not opposed to one

another, as is clear from the examples of colors and shapes.

Reply Obj. 3: Parts can be understood in two ways. First, in a

confused way, as existing in the whole, and thus they are known

through the one form of the whole, and so are known together. In

another way they are known distinctly: thus each is known by its

species; and so they are not understood at the same time.

Reply Obj. 4: If the intellect sees the difference or comparison

between one thing and another, it knows both in relation to their

difference or comparison; just, as we have said above (ad 3), as

it knows the parts in the whole.

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Summa Theologica, Part I (Prima Pars) From the Complete American Edition · 第 531 / 722 题