(1) The controversy over the plurality or unicity of
substantial forms which ranged Augustinian Platonists
like Saint Bonaventura against more radical Aristote-
lians like Aquinas involved questions of matter both
as principle of individuation and as proximate and pure
potentiality. Against the Thomistic doctrine that there
might be numerically distinct instances of things spe-
cifically identical in different “designated (ostensible)
matters,” the Platonists insisted that individuality was
a function of a unique intersection of formal properties.
Thomas' contention that with respect to man, for ex-
ample, “soul is not another form than that through
which three dimensions could be designated in the
thing” (De ente et essentia ii), combined with the
traditional Aristotelian teaching that substantial change
involves a reduction to “prime matter” or “pure po-
tentiality” seemed to deprive levels of form like “cor-
poreity,” “organism,” and “animality” of their func-
tions in nature. The dilemma in which the Aristotelians
found themselves was that if existing substances could
enter into a new substance (e.g., a child) without
modification, the new substance was only a mechanical
combination; but if there was a reduction of all incor-
porated substances to prime matter, it would seem that
one ought to be able to produce any given substance
from any given combination of proximate matters. To
meet this difficulty they developed, beyond anything
found explicitly in Aristotle, a theory of virtutes, or
powers. These powers bore close resemblance to the
substantial forms of the proximate matter prior to its
ingredience in the new substance; they nevertheless
represented some modifications by the new environ-
ment within the substance; and they were potentially
restorable to their original states on the dissolution of
the substance.
