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Newton's Principles Rule
1 We are to admit no more causes of
natural things, than such as are both true and sufficient to explain their
appearances. To this purpose the philosophers
say, that Nature does nothing in vain, and more is in vain, when less will
serve; for Nature is pleased with simplicity, and affects not the pomp of
superfluous causes. Rule
2 Therefore to the same natural
effects we must, as far as possible, assign the same causes. As to respiration in a man, and in
a beast; the descent of stones in Europe and in America; the light of our
culinary fire and of the sun; the reflection of light in the earth, and in
the planets. Rule
3 The qualities of bodies, which
admit neither intension nor remission of degrees, and which are found to
belong to all bodies within reach of our experiments, are to be esteemed the
universal qualities of all bodies whatsoever. For since the qualities of bodies
are known to us by experiments, we are to hold for universal, all such as
universally agree with experiments; and such as are not liable to diminution,
can never be quite taken away. We are certainly not to relinquish the
evidence of experiments for the sake of dreams and vain fictions of our own
devising; nor are we to recede from the analogy of Nature, which is wont to
be simple, and always consonant to itself. We no
other way know the extension of bodies, than by our senses, nor do these
reach it in all bodies; but because we perceive extension in all that are
sensible, therefore we ascribe it universally to all others, also. That
abundance of bodies are hard we learn by experience.
And because the hardness of the whole arises from the hardness of the parts,
we therefore justly infer the hardness of the undivided particles not only of
the bodies we feel but of all others. That all bodies are impenetrable we
gather not from reason, but from sensation. The bodies which we handle we
find impenetrable and thence conclude impenetrability to be a universal
property of all bodies whatsoever. That all bodies are moveable, and endowed
with certain powers (which we call the forces of inertia) or persevering in
their motion or in their rest, we only infer from the like properties
observed in the bodies which we have seen. The extension, hardness,
impenetrability, mobility, and force of inertia of the whole result from the
extension, hardness, impenetrability, mobility, and forces of inertia of the
parts: and thence we conclude that the least particles of all bodies to be
also all extended, and hard, and impenetrable, and moveable, and endowed with
their proper forces of inertia. And this is the foundation of all philosophy.
Moreover, that the divided but contiguous particles of bodies may be
separated from one another, is a matter of observation; and, in the particles
that remain undivided, our minds are able to distinguish yet lesser parts, as
is mathematically demonstrated. But whether the parts so distinguished, and
not yet divided, may, by the powers of nature, be actually divided and
separated from one another, we cannot certainly determine. Yet had we the
proof of but one experiment, that any undivided particle, in breaking a hard
and solid body, suffered a division, we might by virtue of this rule,
conclude, that the undivided as well as the divided particles, may be divided
and actually separated into infinity. Lastly, if it universally appears,
by experiments and astronomical observations, that all bodies about the
earth, gravitate toward the earth; and that in proportion to the quantity of
matter which they severally contain; that the moon likewise, according to the
quantity of its matter, gravitates toward the earth; that on the other hand
our sea gravitates toward the moon; and all the planets mutually one toward
another; and the comets in like manner towards the sun; we must, in
consequence of this rule, universally allow, that all bodies whatsoever are
endowed with a principle of mutual gravitation. For the argument from the
appearances concludes with more force for the universal gravitation of all
bodies, than for their impenetrability, of which among those in the celestial
regions, we have no experiments, nor any manner of observation. Not that I
affirm gravity to be essential to all bodies. By their inherent force I mean
nothing but their force of inertia. This is immutable. Their gravity is
diminished as they recede from the earth. Rule
4 In experimental philosophy we are
to look upon propositions collected by general induction from phenomena as
accurately or very nearly true, notwithstanding any contrary hypotheses that
may be imagined, till such time as other phenomena occur, by which they may
either be made more accurate, or liable to exceptions. This rule we must follow that the
argument of induction may not be evaded by hypotheses. |
