It may be difficult to overestimate Spinoza's influence on Western thought. In The Ethics, published in 1677, he wrote:
“a
body in motion keeps in motion, until it is determined to a state of rest by
some other body; and a body at rest remains so, until it is determined to a state
of motion by some other body” (II. Axiom II.
Lemma III. Corollary) A quite long explanation follows. It’s not
quite Sir Isaac Newton’s three laws of motion (1686); but it’s close enough to
speculate about influence.
Rousseau’s The Social Contract was published in 1762. The rather long passage below resonates with those ideas.
“Every man exists by sovereign natural right, and,
consequently, by sovereign natural right performs those actions
which follow from the necessity of his own nature; therefore by
sovereign natural right every man judges what is good and what is
bad, takes care of his own advantage according to his own
disposition (IV. xix. and IV. xx.), avenges the wrongs done to
him (III. xl. Coroll. ii.), and endeavours to preserve that which
he loves and to destroy that which he hates (III. xxviii.). Now,
if men lived under the guidance of reason, everyone would remain
in possession of this his right, without any injury being done to
his neighbour (IV. xxxv. Coroll. i.). But seeing that they are a
prey to their emotions, which far surpass human power or virtue
(IV. vi.), they are often drawn in different directions, and
being at variance one with another (IV. xxxiii. xxxiv.), stand in
need of mutual help (IV. xxxv. note). Wherefore, in order that
men may live together in harmony, and may aid one another, it is
necessary that they should forego their natural right, and, for
the sake of security, refrain from all actions which can injure
their fellow--men. The way in which this end can be obtained, so
that men who are necessarily a prey to their emotions (IV. iv.
Coroll.), inconstant, and diverse, should be able to render each
other mutually secure, and feel mutual trust, is evident from IV.
vii. and III. xxxix. It is there shown, that an emotion can only
be restrained by an emotion stronger than, and contrary to
itself, and that men avoid inflicting injury through fear of
incurring a greater injury themselves.
“On this law society can be established, so long as it keeps
in its own hand the right, possessed by everyone, of avenging
injury, and pronouncing on good and evil; and provided it also
possesses the power to lay down a general rule of conduct, and to
pass laws sanctioned, not by reason, which is powerless in
restraining emotion, but by threats (IV. xvii. note). Such a
society established with laws and the power of preserving itself
is called a State, while those who live under its protection are
called citizens” (IV. XXXVII. note II.)
