Letters on England [29]
that two and
two make four for no other reason but because God would have it so.
However, it will not be making him too great a compliment if we
affirm that he was valuable even in his mistakes. He deceived
himself; but then it was at least in a methodical way. He destroyed
all the absurd chimeras with which youth had been infatuated for two
thousand years. He taught his contemporaries how to reason, and
enabled them to employ his own weapons against himself. If
Descartes did not pay in good money, he however did great service in
crying down that of a base alloy.
I indeed believe that very few will presume to compare his
philosophy in any respect with that of Sir Isaac Newton. The former
is an essay, the latter a masterpiece. But then the man who first
brought us to the path of truth, was perhaps as great a genius as he
who afterwards conducted us through it.
Descartes gave sight to the blind. These saw the errors of
antiquity and of the sciences. The path he struck out is since
become boundless. Rohault's little work was, during some years, a
complete system of physics; but now all the Transactions of the
several academies in Europe put together do not form so much as the
beginning of a system. In fathoming this abyss no bottom has been
found. We are now to examine what discoveries Sir Isaac Newton has
made in it.
LETTER XV.--ON ATTRACTION
The discoveries which gained Sir Isaac Newton so universal a
reputation, relate to the system of the world, to light, to
geometrical infinities; and, lastly, to chronology, with which he
used to amuse himself after the fatigue of his severer studies.
I will now acquaint you (without prolixity if possible) with the few
things I have been able to comprehend of all these sublime ideas.
With regard to the system of our world, disputes were a long time
maintained, on the cause that turns the planets, and keeps them in
their orbits: and on those causes which make all bodies here below
descend towards the surface of the earth.
The system of Descartes, explained and improved since his time,
seemed to give a plausible reason for all those phenomena; and this
reason seemed more just, as it is simple and intelligible to all
capacities. But in philosophy, a student ought to doubt of the
things he fancies he understands too easily, as much as of those he
does not understand.
Gravity, the falling of accelerated bodies on the earth, the
revolution of the planets in their orbits, their rotations round
their axis, all this is mere motion. Now motion cannot perhaps be
conceived any otherwise than by impulsion; therefore all those
bodies must be impelled. But by what are they impelled? All space
is full, it therefore is filled with a very subtile matter, since
this is imperceptible to us; this matter goes from west to east,
since all the planets are carried from west to east. Thus from
hypothesis to hypothesis, from one appearance to another,
philosophers have imagined a vast whirlpool of subtile matter, in
which the planets are carried round the sun: they also have created
another particular vortex which floats in the great one, and which
turns daily round the planets. When all this is done, it is
pretended that gravity depends on this diurnal motion; for, say
these, the velocity of the subtile matter that turns round our
little vortex, must be seventeen times more rapid than that of the
earth; or, in case its velocity is seventeen times greater than that
of the earth, its centrifugal force must be vastly greater, and
consequently impel all bodies towards the earth. This is the cause
of gravity, according to the Cartesian system. But the theorist,
before he calculated the centrifugal force and velocity of the
subtile matter, should first have been certain that it existed.
Sir Isaac Newton, seems to have destroyed all these great and little
vortices,
two make four for no other reason but because God would have it so.
However, it will not be making him too great a compliment if we
affirm that he was valuable even in his mistakes. He deceived
himself; but then it was at least in a methodical way. He destroyed
all the absurd chimeras with which youth had been infatuated for two
thousand years. He taught his contemporaries how to reason, and
enabled them to employ his own weapons against himself. If
Descartes did not pay in good money, he however did great service in
crying down that of a base alloy.
I indeed believe that very few will presume to compare his
philosophy in any respect with that of Sir Isaac Newton. The former
is an essay, the latter a masterpiece. But then the man who first
brought us to the path of truth, was perhaps as great a genius as he
who afterwards conducted us through it.
Descartes gave sight to the blind. These saw the errors of
antiquity and of the sciences. The path he struck out is since
become boundless. Rohault's little work was, during some years, a
complete system of physics; but now all the Transactions of the
several academies in Europe put together do not form so much as the
beginning of a system. In fathoming this abyss no bottom has been
found. We are now to examine what discoveries Sir Isaac Newton has
made in it.
LETTER XV.--ON ATTRACTION
The discoveries which gained Sir Isaac Newton so universal a
reputation, relate to the system of the world, to light, to
geometrical infinities; and, lastly, to chronology, with which he
used to amuse himself after the fatigue of his severer studies.
I will now acquaint you (without prolixity if possible) with the few
things I have been able to comprehend of all these sublime ideas.
With regard to the system of our world, disputes were a long time
maintained, on the cause that turns the planets, and keeps them in
their orbits: and on those causes which make all bodies here below
descend towards the surface of the earth.
The system of Descartes, explained and improved since his time,
seemed to give a plausible reason for all those phenomena; and this
reason seemed more just, as it is simple and intelligible to all
capacities. But in philosophy, a student ought to doubt of the
things he fancies he understands too easily, as much as of those he
does not understand.
Gravity, the falling of accelerated bodies on the earth, the
revolution of the planets in their orbits, their rotations round
their axis, all this is mere motion. Now motion cannot perhaps be
conceived any otherwise than by impulsion; therefore all those
bodies must be impelled. But by what are they impelled? All space
is full, it therefore is filled with a very subtile matter, since
this is imperceptible to us; this matter goes from west to east,
since all the planets are carried from west to east. Thus from
hypothesis to hypothesis, from one appearance to another,
philosophers have imagined a vast whirlpool of subtile matter, in
which the planets are carried round the sun: they also have created
another particular vortex which floats in the great one, and which
turns daily round the planets. When all this is done, it is
pretended that gravity depends on this diurnal motion; for, say
these, the velocity of the subtile matter that turns round our
little vortex, must be seventeen times more rapid than that of the
earth; or, in case its velocity is seventeen times greater than that
of the earth, its centrifugal force must be vastly greater, and
consequently impel all bodies towards the earth. This is the cause
of gravity, according to the Cartesian system. But the theorist,
before he calculated the centrifugal force and velocity of the
subtile matter, should first have been certain that it existed.
Sir Isaac Newton, seems to have destroyed all these great and little
vortices,