QUESTION 15: OF THE VICES OPPOSED TO KNOWLEDGE AND UNDERSTANDING
We must now consider the vices opposed to knowledge and understanding.
Since, however, we have treated of ignorance which is opposed to
knowledge, when we were discussing the causes of sins (FS, Question ), we
must now inquire about blindness of mind and dulness of sense, which are
opposed to the gift of understanding; and under this head there are three
points of inquiry:
(1) Whether blindness of mind is a sin?
(2) Whether dulness of sense is a sin distinct from blindness of mind?
(3) Whether these vices arise from sins of the flesh?
Article 1: Whether blindness of mind is a sin?
Objection 1: It would seem that blindness of mind is not a sin. Because,
seemingly, that which excuses from sin is not itself a sin. Now blindness
of mind excuses from sin; for it is written (Jn. 9:41): "If you were
blind, you should not have sin." Therefore blindness of mind is not a sin.
Objection 2: Further, punishment differs from guilt. But blindness of mind is
a punishment as appears from Is. 6:10, "Blind the heart of this people,"
for, since it is an evil, it could not be from God, were it not a
punishment. Therefore blindness of mind is not a sin.
Objection 3: Further, every sin is voluntary, according to Augustine (De Vera
Relig. xiv). Now blindness of mind is not voluntary, since, as Augustine
says (Confess. x), "all love to know the resplendent truth," and as we
read in Eccles. 11:7, "the light is sweet and it is delightful for the
eyes to see the sun." Therefore blindness of mind is not a sin.
On the contrary, Gregory (Moral. xxxi, 45) reckons blindness of mind
among the vices arising from lust.
I answer that, Just as bodily blindness is the privation of the
principle of bodily sight, so blindness of mind is the privation of the
principle of mental or intellectual sight. Now this has a threefold
principle. One is the light of natural reason, which light, since it
pertains to the species of the rational soul, is never forfeit from the
soul, and yet, at times, it is prevented from exercising its proper act,
through being hindered by the lower powers which the human intellect
needs in order to understand, for instance in the case of imbeciles and
madmen, as stated in the FP, Question , Articles ,8.
Another principle of intellectual sight is a certain habitual light
superadded to the natural light of reason, which light is sometimes
forfeit from the soul. This privation is blindness, and is a punishment,
in so far as the privation of the light of grace is a punishment. Hence
it is written concerning some (Wis. 2:21): "Their own malice blinded
A third principle of intellectual sight is an intelligible principle,
through which a man understands other things; to which principle a man
may attend or not attend. That he does not attend thereto happens in two
ways. Sometimes it is due to the fact that a man's will is deliberately
turned away from the consideration of that principle, according to Ps.
35:4, "He would not understand, that he might do well": whereas sometimes
it is due to the mind being more busy about things which it loves more,
so as to be hindered thereby from considering this principle, according
to Ps. 57:9, "Fire," i.e. of concupiscence, "hath fallen on them and they
shall not see the sun." In either of these ways blindness of mind is a
Reply to Objection 1: The blindness that excuses from sin is that which arises
from the natural defect of one who cannot see.
Reply to Objection 2: This argument considers the second kind of blindness which
is a punishment.
Reply to Objection 3: To understand the truth is, in itself, beloved by all; and
yet, accidentally it may be hateful to someone, in so far as a man is
hindered thereby from having what he loves yet more.
Article 2: Whether dulness of sense is a sin distinct from blindness of mind?
Objection 1: It seems that dulness of sense is not a distinct sin from
blindness of mind. Because one thing has one contrary. Now dulness is
opposed to the gift of understanding, according to Gregory (Moral. ii,
49); and so is blindness of mind, since understanding denotes a principle
of sight. Therefore dulness of sense is the same as blindness of mind.
Objection 2: Further, Gregory (Moral. xxxi, 45) in speaking of dulness
describes it as "dullness of sense in respect of understanding." Now
dulness of sense in respect of understanding seems to be the same as a
defect in understanding, which pertains to blindness of mind. Therefore
dulness of sense is the same as blindness of mind.
Objection 3: Further, if they differ at all, it seems to be chiefly in the
fact that blindness of mind is voluntary, as stated above (Article ), while
dulness of sense is a natural defect. But a natural defect is not a sin:
so that, accordingly, dulness of sense would not be a sin, which is
contrary to what Gregory says (Moral. xxxi, 45), where he reckons it
among the sins arising from gluttony.
On the contrary, Different causes produce different effects. Now Gregory
says (Moral. xxxi, 45) that dulness of sense arises from gluttony, and
that blindness of mind arises from lust. Now these others are different
vices. Therefore those are different vices also.
I answer that, Dull is opposed to sharp: and a thing is said to be sharp
because it can pierce; so that a thing is called dull through being
obtuse and unable to pierce. Now a bodily sense, by a kind of metaphor,
is said to pierce the medium, in so far as it perceives its object from a
distance or is able by penetration as it were to perceive the smallest
details or the inmost parts of a thing. Hence in corporeal things the
senses are said to be acute when they can perceive a sensible object from
afar, by sight, hearing, or scent, while on the other hand they are said
to be dull, through being unable to perceive, except sensible objects
that are near at hand, or of great power.
Now, by way of similitude to bodily sense, we speak of sense in
connection with the intellect; and this latter sense is in respect of
certain primals and extremes, as stated in Ethic. vi, even as the senses
are cognizant of sensible objects as of certain principles of knowledge.
Now this sense which is connected with understanding, does not perceive
its object through a medium of corporeal distance, but through certain
other media, as, for instance, when it perceives a thing's essence
through a property thereof, and the cause through its effect.
Consequently a man is said to have an acute sense in connection with his
understanding, if, as soon as he apprehends a property or effect of a
thing, he understands the nature or the thing itself, and if he can
succeed in perceiving its slightest details: whereas a man is said to
have a dull sense in connection with his understanding, if he cannot
arrive at knowing the truth about a thing, without many explanations; in
which case, moreover, he is unable to obtain a perfect perception of
everything pertaining to the nature of that thing.
Accordingly dulness of sense in connection with understanding denotes a certain weakness of the mind as to the consideration of spiritual goods; while blindness of mind implies the complete privation of the knowledge of such things. Both are opposed to the gift of understanding, whereby a man knows spiritual goods by apprehending them, and has a subtle penetration of their inmost nature. This dulness has the character of sin, just as blindness of mind has, that is, in so far as it is voluntary, as evidenced in one who, owing to his affection for carnal things, dislikes or neglects the careful consideration of spiritual things.
This suffices for the Replies to the Objections.
Article 3: Whether blindness of mind and dulness of sense arise from sins of the flesh?
Objection 1: It would seem that blindness of mind and dulness of sense do not
arise from sins of the flesh. For Augustine (Retract. i, 4) retracts what
he had said in his Soliloquies i, 1, "God Who didst wish none but the
clean to know the truth," and says that one might reply that "many, even
those who are unclean, know many truths." Now men become unclean chiefly
by sins of the flesh. Therefore blindness of mind and dulness of sense
are not caused by sins of the flesh.
Objection 2: Further, blindness of mind and dulness of sense are defects in
connection with the intellective part of the soul: whereas carnal sins
pertain to the corruption of the flesh. But the flesh does not act on the
soul, but rather the reverse. Therefore the sins of the flesh do not
cause blindness of mind and dulness of sense.
Objection 3: Further, all things are more passive to what is near them than to
what is remote. Now spiritual vices are nearer the mind than carnal vices
are. Therefore blindness of mind and dulness of sense are caused by
spiritual rather than by carnal vices.
On the contrary, Gregory says (Moral. xxxi, 45) that dulness of sense
arises from gluttony and blindness of mind from lust.
I answer that, The perfect intellectual operation in man consists in an
abstraction from sensible phantasms, wherefore the more a man's intellect
is freed from those phantasms, the more thoroughly will it be able to
consider things intelligible, and to set in order all things sensible.
Thus Anaxagoras stated that the intellect requires to be "detached" in
order to command, and that the agent must have power over matter, in
order to be able to move it. Now it is evident that pleasure fixes a
man's attention on that which he takes pleasure in: wherefore the
Philosopher says (Ethic. x, 4,5) that we all do best that which we take
pleasure in doing, while as to other things, we do them either not at
all, or in a faint-hearted fashion.
Now carnal vices, namely gluttony and lust, are concerned with pleasures
of touch in matters of food and sex; and these are the most impetuous of
all pleasures of the body. For this reason these vices cause man's
attention to be very firmly fixed on corporeal things, so that in
consequence man's operation in regard to intelligible things is weakened,
more, however, by lust than by gluttony, forasmuch as sexual pleasures
are more vehement than those of the table. Wherefore lust gives rise to
blindness of mind, which excludes almost entirely the knowledge of
spiritual things, while dulness of sense arises from gluttony, which
makes a man weak in regard to the same intelligible things. On the other
hand, the contrary virtues, viz. abstinence and chastity, dispose man
very much to the perfection of intellectual operation. Hence it is
written (Dan. 1:17) that "to these children" on account of their
abstinence and continency, "God gave knowledge and understanding in every
book, and wisdom."
Reply to Objection 1: Although some who are the slaves of carnal vices are at
times capable of subtle considerations about intelligible things, on
account of the perfection of their natural genius, or of some habit
superadded thereto, nevertheless, on account of the pleasures of the
body, it must needs happen that their attention is frequently withdrawn
from this subtle contemplation: wherefore the unclean can know some
truths, but their uncleanness is a clog on their knowledge.
Reply to Objection 2: The flesh acts on the intellective faculties, not by
altering them, but by impeding their operation in the aforesaid manner.
Reply to Objection 3: It is owing to the fact that the carnal vices are further
removed from the mind, that they distract the mind's attention to more
remote things, so that they hinder the mind's contemplation all the more.