BOOK I PART III
the illustrations upon it.) There are some, who
maintain, that bodies operate by their substan-
tial form; others, by their accidents or quali-
ties; several, by their matter and form; some,
by their form and accidents; others, by certain
virtues and faculties distinct from all this. All
these sentiments again are mixed and varyed
in a thousand different ways; and form a strong
presumption, that none of them have any solid-
ity or evidence, and that the supposition of an
efficacy in any of the known qualities of matter
is entirely without foundation. This presump-
tion must encrease upon us, when we consider,
that these principles of substantial forms, and
accidents, and faculties, are not in reality any
of the known properties of bodies, but are per-
fectly unintelligible and inexplicable. For it is
evident philosophers would never have had
recourse to such obscure and uncertain prin-