Whether Our Intellect Can Understand Immaterial Substances Through Its
Knowledge of Material Things?
Objection 1: It would seem that our intellect can know immaterial
substances through the knowledge of material things. For Dionysius
says (Coel. Hier. i) that "the human mind cannot be raised up to
immaterial contemplation of the heavenly hierarchies, unless it is
led thereto by material guidance according to its own nature."
Therefore we can be led by material things to know immaterial
substances.
Obj. 2: Further, science resides in the intellect. But there are
sciences and definitions of immaterial substances; for Damascene
defines an angel (De Fide Orth. ii, 3); and we find angels treated of
both in theology and philosophy. Therefore immaterial substances can
be understood by us.
Obj. 3: Further, the human soul belongs to the genus of immaterial
substances. But it can be understood by us through its act by which
it understands material things. Therefore also other material
substances can be understood by us, through their material effects.
Obj. 4: Further, the only cause which cannot be comprehended through
its effects is that which is infinitely distant from them, and this
belongs to God alone. Therefore other created immaterial substances
can be understood by us through material things.
_On the contrary,_ Dionysius says (Div. Nom. i) that "intelligible
things cannot be understood through sensible things, nor composite
things through simple, nor incorporeal through corporeal."
_I answer that,_ Averroes says (De Anima iii) that a philosopher
named Avempace [*Ibn-Badja, Arabian Philosopher; ob. 1183] taught
that by the understanding of natural substances we can be led,
according to true philosophical principles, to the knowledge of
immaterial substances. For since the nature of our intellect is to
abstract the quiddity of material things from matter, anything
material residing in that abstracted quiddity can again be made
subject to abstraction; and as the process of abstraction cannot go
on forever, it must arrive at length at some immaterial quiddity,
absolutely without matter; and this would be the understanding of
immaterial substance.
Now this opinion would be true, were immaterial substances the forms
and species of these material things; as the Platonists supposed.
But supposing, on the contrary, that immaterial substances differ
altogether from the quiddity of material things, it follows that
however much our intellect abstract the quiddity of material things
from matter, it could never arrive at anything akin to immaterial
substance. Therefore we are not able perfectly to understand
immaterial substances through material substances.
Reply Obj. 1: From material things we can rise to some kind of
knowledge of immaterial things, but not to the perfect knowledge
thereof; for there is no proper and adequate proportion between
material and immaterial things, and the likenesses drawn from
material things for the understanding of immaterial things are
very dissimilar therefrom, as Dionysius says (Coel. Hier. ii).
Reply Obj. 2: Science treats of higher things principally by way of
negation. Thus Aristotle (De Coel. i, 3) explains the heavenly bodies
by denying to them inferior corporeal properties. Hence it follows
that much less can immaterial substances be known by us in such a way
as to make us know their quiddity; but we may have a scientific
knowledge of them by way of negation and by their relation to
material things.
Reply Obj. 3: The human soul understands itself through its own act
of understanding, which is proper to it, showing perfectly its power
and nature. But the power and nature of immaterial substances cannot
be perfectly known through such act, nor through any other material
thing, because there is no proportion between the latter and the
power of the former.
Reply Obj. 4: Created immaterial substances are not in the same
natural genus as material substances, for they do not agree in power
or in matter; but they belong to the same logical genus, because even
immaterial substances are in the predicament of substance, as their
essence is distinct from their existence. But God has no connection
with material things, as regards either natural genus or logical
genus; because God is in no genus, as stated above (Q. 3, A. 5).
Hence through the likeness derived from material things we can know
something positive concerning the angels, according to some common
notion, though not according to the specific nature; whereas we
cannot acquire any such knowledge at all about God.
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