To the best of my knowledge Des Cartes was the first philosopher who
introduced the absolute and essential heterogenity of the soul as
intelligence, and the body as matter. The assumption, and the form of
speaking have remained, though the denial of all other properties to
matter but that of extension, on which denial the whole system of
Dualism is grounded, has been long exploded. For since impenetrability
is intelligible only as a mode of resistance; its admission places the
essence of matter in an act or power, which it possesses in common
with spirit; and body and spirit are therefore no longer absolutely
heterogeneous, but may without any absurdity be supposed to be
different modes, or degrees in perfection, of a common substratum. To
this possibility, however, it was not the fashion to advert. The soul
was a thinking substance, and body a space-filling substance. Yet the
apparent action of each on the other pressed heavy on the philosopher
on the one hand; and no less heavily on the other hand pressed the
evident truth, that the law of causality holds only between
homogeneous things, that is, things having some common property; and
cannot extend from one world into another, its contrary. A close
analysis evinced it to be no less absurd than the question whether a
man's affection for his wife lay North-east, or South-west of the love
he bore towards his child. Leibnitz's doctrine of a pre-established
harmony; which he certainly borrowed from Spinoza, who had himself
taken the hint from Des Cartes's animal machines, was in its common
interpretation too strange to survive the inventor—too repugnant to
our common sense; which is not indeed entitled to a judicial voice in
the courts of scientific philosophy; but whose whispers still exert a
strong secret influence. Even Wolf, the admirer and illustrious
systematizer of the Leibnitzian doctrine, contents himself with
defending the possibility of the idea, but does not adopt it as a part
of the edifice.

The hypothesis of Hylozoism, on the other side, is the death of all
rational physiology, and indeed of all physical science; for that
requires a limitation of terms, and cannot consist with the arbitrary
power of multiplying attributes by occult qualities. Besides, it
answers no purpose; unless, indeed, a difficulty can be solved by
multiplying it, or we can acquire a clearer notion of our soul by
being told that we have a million of souls, and that every atom of our
bodies has a soul of its own. Far more prudent is it to admit the
difficulty once for all, and then let it lie at rest. There is a
sediment indeed at the bottom of the vessel, but all the water above
it is clear and transparent. The Hylozoist only shakes it up, and
renders the whole turbid.

But it is not either the nature of man, or the duty of the philosopher
to despair concerning any important problem until, as in the squaring
of the circle, the impossibility of a solution has been demonstrated.
How the esse assumed as originally distinct from the scire, can ever
unite itself with it; how being can transform itself into a knowing,
becomes conceivable on one only condition; namely, if it can be shown
that the vis representativa, or the Sentient, is itself a species of
being; that is, either as a property or attribute, or as an hypostasis
or self subsistence. The former—that thinking is a property of matter
under particular conditions,—is, indeed, the assumption of
materialism; a system which could not but be patronized by the
philosopher, if only it actually performed what it promises. But how
any affection from without can metamorphose itself into perception or
will, the materialist has hitherto left, not only as incomprehensible
as he found it, but has aggravated it into a comprehensible absurdity.
For, grant that an object from without could act upon the conscious
self, as on a consubstantial object; yet such an affection could only
engender something homogeneous with itself. Motion could only
propagate motion. Matter has no Inward. We remove one surface, but to
meet with another. We can but divide a particle into particles; and
each atom comprehends in itself the properties of the material
universe. Let any reflecting mind make the experiment of explaining to
itself the evidence of our sensuous intuitions, from the hypothesis
that in any given perception there is a something which has been
communicated to it by an impact, or an impression ab extra. In the
first place, by the impact on the percipient, or ens representans, not
the object itself, but only its action or effect, will pass into the
same. Not the iron tongue, but its vibrations, pass into the metal of
the bell. Now in our immediate perception, it is not the mere power or
act of the object, but the object itself, which is immediately
present. We might indeed attempt to explain this result by a chain of
deductions and conclusions; but that, first, the very faculty of
deducing and concluding would equally demand an explanation; and
secondly, that there exists in fact no such intermediation by logical
notions, such as those of cause and effect. It is the object itself,
not the product of a syllogism, which is present to our consciousness.
Or would we explain this supervention of the object to the sensation,
by a productive faculty set in motion by an impulse; still the
transition, into the percipient, of the object itself, from which the
impulse proceeded, assumes a power that can permeate and wholly
possess the soul,

    And like a God by spiritual art,
    Be all in all, and all in every part.
                                   [Cowley]

And how came the percipient here? And what is become of the wonder-
promising Matter, that was to perform all these marvels by force of
mere figure, weight and motion? The most consistent proceeding of the
dogmatic materialist is to fall back into the common rank of soul-and-
bodyists; to affect the mysterious, and declare the whole process a
revelation given, and not to be understood, which it would be profane
to examine too closely. Datur non intelligitur. But a revelation
unconfirmed by miracles, and a faith not commanded by the conscience,
a philosopher may venture to pass by, without suspecting himself of
any irreligious tendency.

Thus, as materialism has been generally taught, it is utterly
unintelligible, and owes all its proselytes to the propensity so
common among men, to mistake distinct images for clear conceptions;
and vice versa, to reject as inconceivable whatever from its own
nature is unimaginable. But as soon as it becomes intelligible, it
ceases to be materialism. In order to explain thinking, as a material
phaenomenon, it is necessary to refine matter into a mere modification
of intelligence, with the two-fold function of appearing and
perceiving. Even so did Priestley in his controversy with Price. He
stripped matter of all its material properties; substituted spiritual
powers; and when we expected to find a body, behold! we had nothing
but its ghost—the apparition of a defunct substance!

I shall not dilate further on this subject; because it will, (if God
grant health and permission), be treated of at large and
systematically in a work, which I have many years been preparing, on
the Productive Logos human and divine; with, and as the introduction
to, a full commentary on the Gospel of St. John. To make myself
intelligible as far as my present subject requires, it will be
sufficient briefly to observe.—1. That all association demands and
presupposes the existence of the thoughts and images to be
associated.—2. That the hypothesis of an external world exactly
correspondent to those images or modifications of our own being, which
alone, according to this system, we actually behold, is as thorough
idealism as Berkeley's, inasmuch as it equally, perhaps in a more
perfect degree, removes all reality and immediateness of perception,
and places us in a dream-world of phantoms and spectres, the
inexplicable swarm and equivocal generation of motions in our own
brains.—3. That this hypothesis neither involves the explanation, nor
precludes the necessity, of a mechanism and co-adequate forces in the
percipient, which at the more than magic touch of the impulse from
without is to create anew for itself the correspondent object. The
formation of a copy is not solved by the mere pre-existence of an
original; the copyist of Raffael's Transfiguration must repeat more or
less perfectly the process of Raffael. It would be easy to explain a
thought from the image on the retina, and that from the geometry of
light, if this very light did not present the very same difficulty. We
might as rationally chant the Brahim creed of the tortoise that
supported the bear, that supported the elephant, that supported the
world, to the tune of "This is the house that Jack built." The sic Deo
placitum est we all admit as the sufficient cause, and the divine
goodness as the sufficient reason; but an answer to the Whence and Why
is no answer to the How, which alone is the physiologist's concern. It
is a sophisma pigrum, and (as Bacon hath said) the arrogance of
pusillanimity, which lifts up the idol of a mortal's fancy and
commands us to fall down and worship it, as a work of divine wisdom,
an ancile or palladium fallen from heaven. By the very same argument
the supporters of the Ptolemaic system might have rebuffed the
Newtonian, and pointing to the sky with self-complacent grin [26] have
appealed to common sense, whether the sun did not move and the earth
stand still.     

FOOTNOTE  [by Samuel Taylor Coleridge]