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LXVI.
So much then for the mischievous authorities of
systems, which are founded either on common notions, or on a few
experiments, or on superstition. It remains to speak of the faulty
subject-matter of contemplations, especially in natural philosophy.
Now the human understanding is infected by the sight of what takes
place in the mechanical arts, in which the alteration of bodies
proceeds chiefly by composition or separation, and so imagines that
something similar goes on in the universal nature of things. From
this source has flowed the fiction of elements, and of their
concourse for the formation of natural bodies. Again, when man
contemplates nature working freely, he meets with different species
of things, of animals, of plants, of minerals; whence he readily
passes into the opinion that there are in nature certain primary
forms which nature intends to educe, and that the remaining variety
proceeds from hindrances and aberrations of nature in the fulfilment
of her work, or from the collision of different species and the
transplanting of one into another. To the first of these
speculations we owe our primary qualities of the elements; to the
other our occult properties and specific virtues; and both of them
belong to those empty compendia of thought wherein the mind
rests, and whereby it is diverted from more solid pursuits. It is
to better purpose that the physicians bestow their labour on the
secondary qualities of matter, and the operations of attraction,
repulsion, attenuation, conspissation, dilatation, astriction,
dissipation, maturation, and the like; and were it not that by those
two compendia which I have mentioned (elementary qualities, to wit,
and specific virtues) they corrupted their correct observations in
these other matters, -- either reducing them to first qualities and
their subtle and incommensurable mixtures, or not following them out
with greater and more diligent observation to third and fourth
qualities, but breaking off the scrutiny prematurely, -- they had
made much greater progress. Nor are powers of this kind (I do not
say the same, but similar) to be sought for only in the medicines of
the human body, but also in the changes of all other bodies.
But it is a far greater evil that they make the
quiescent principles, wherefrom, and not the moving
principles, whereby, things are produced, the object of their
contemplation and inquiry. For the former tend to discourse, the
latter to works. Nor is there any value in those vulgar
distinctions of motion which are observed in the received system of
natural philosophy, as generation, corruption, augmentation,
diminution, alteration, and local motion. What they mean no doubt
is this: -- if a body, in other respects not changed, be moved from
its place, this is local motion; if without change of place
or essence, it be changed in quality, this is alteration; if
by reason of the change the mass and quantity of the body do not
remain the same, this is augmentation or diminution;
if they be changed to such a degree that they change their very
essence and substance and turn to something else, this is
generation and corruption. But all this is merely
popular, and does not at all go deep into nature; for these are only
measures and limits, not kinds of motion. What they intimate is
how far, not by what means, or from what
source. For they do not suggest anything with regard either to
the desires of bodies or to the development of their parts: it is
only when that motion presents the thing grossly and palpably to the
sense as different from what it was, that they begin to mark the
division. Even when they wish to suggest something with regard to
the causes of motion, and to establish a division with reference to
them, they introduce with the greatest negligence a distinction
between motion natural and violent; a distinction which is itself
drawn entirely from a vulgar notion, since all violent motion is
also in fact natural; the external efficient simply setting nature
working otherwise than it was before. But if, leaving all this, any
one shall observe (for instance) that there is in bodies a desire of
mutual contact, so as not to suffer the unity of nature to be quite
separated or broken and a vacuum thus made; or if any one say that
there is in bodies a desire of resuming their natural dimensions or
tension, so that if compressed within or extended beyond them, they
immediately strive to recover themselves, and fall back to their old
volume and extent; or if any one say that there is in bodies a
desire of congregating towards masses of kindred nature, -- of dense
bodies, for instance, towards the globe of the earth, of thin and
rare bodies towards the compass of the sky; all these and the like
are truly physical kinds of motion; -- but those others are entirely
logical and scholastic, as is abundantly manifest from this
comparison.
Nor again is it a less evil, that in their
philosophies and contemplations their labour is spent in
investigating and handling the first principles of things and the
highest generalities of nature; whereas utility and the means of
working result entirely from things intermediate. Hence it is that
men cease not from abstracting nature till they come to potential
and uninformed matter, nor on the other hand from dissecting nature
till they reach the atom; things which, even if true, can do but
little for the welfare of mankind.
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