358 LAPLACE. 
analysis. No philosopher, no mathematician, could have — 
maintained himself more cautiously on his guard against 
a propensity to hasty speculation. No person dreaded 
more the scientific errors which the imagination gives 
birth to, when it ceases to remain within the limits of 
facts, of calculation, and of analogy. Once, and once 
only, did Laplace launch forward, like Kepler, like 
Descartes, like Leibnitz, like Buffon, into the region of 
conjectures. His conception was not then less than a 
cosmogony. 
All the planets revolve around the sun, from west to 
east, and in planes which include angles of inconsiderable 
magnitude. 
The satellites revolve around their respective prima- 
ries in the same direction as that in which the planets 
revolve around the sun, that is to say, from west to east. 
The planets and satellites which have been found to 
have a rotatory motion, turn also upon their axes from 
west to east. Finally, the rotation of the sun is directed 
from west to east. We have here then an assemblage 
of forty-three movements, all operating in the same di- 
rection. By the calculus of probabilities, the odds are 
four thousand millions to one, that this coincidence in the 
direction of so many movements is not the effect of acci- 
dent. 
It was Buffon, I think, who first attempted to explain 
this singular feature of our solar system. Having wished, 
in the explanation of phenomena, to avoid all recourse 
to causes which were not warranted by nature, the cele- 
brated academician investigated a physical origin of the 
system in what was common to the movements of so 
many bodies differing in magnitude, in form, and in dis- 
tance from the principal centre of attraction. He im- 
