546 THE POPULAR SCIENCE MONTHLY 
The work from which Kant quoted a justification of Descartes’s enter- 
prise—and, by implication, of his own—the “ Universal History ” 
(1736-65) appeared in an (incomplete) German translation in 1744. 
This huge historical compilation, one of the great publishing enterprises 
of the time, contained an introduction of (in the German edition) over 
one hundred pages devoted to the subject of cosmogony, giving the the- 
ories of the Greek philosophers, of Descartes, Burnet, Whiston and other 
moderns, and a new hypothesis of the author’s own. In 1749 the first 
volume of a still more celebrated, and scarcely less voluminous, publica- 
tion—Buffon’s “ Histoire Naturelle ”—saw the light. This volume was 
chiefly devoted to a “history and theory of the earth,” with a chapter 
on the formation of planets which contained ideas more closely related 
than those of Kant to the nebular hypothesis. Buffon remarked upon 
the peculiar uniformities of the solar system which seemed to call for a 
mechanical explanation, but which gravitation alone did not account 
for, viz., the revolution of all the planets in the same direction, approxi- 
mately in the same plane, and in nearly circular orbits. Buffon’s own 
explanation of these phenomena in his “ Théorie de la Terre” of 1749 
is given in the following passages : 
This uniformity of position and direction in the movement of the planets 
necessarily presupposes some common factor in their original movement of 
impulsion, and makes us suspect that it has been communicated to them by one 
and the same cause. ... This impulsive force was certainly imparted to the 
stars in general by the hand of God when he set the universe in motion. But 
since, in physical science, we ought to abstain so far as possible from having 
recourse to causes outside of nature, it seems to me that in the solar system we 
can account for this impelling force in a sufficiently probable manner and in 
accordance with the principles of mechanics. ... May it not with some proba- 
bility be imagined that a comet falling upon the surface of the sun may have 
separated from that body certain parts, to which it has communicated a move- 
ment of impulsion in a common direction? . . . The planets would thus have 
formerly belonged to the sun, and would have been detached from it by an 
impelling force, common to all alike, which they still retain.” 
Buffon was the only one" of his precursors (of the post-Newtonian 
period) known to Laplace. He made this passage of the “ Histoire 
Naturelle” the starting point of his own earliest exposition of his 
nebular hypothesis, in the concluding chapter of the “Systeme du 
Monde.” The hypothesis of Buffon, he remarked, accounted for most 
of the non-gravitational peculiarities of planetary motion that require 
to be accounted for; but since there remained certain other such phe- 
nomena which Buffon’s supposition could not explain, a new hypothesis 
must be devised. 
Finally, in the same year, 1749, a generation after its famous 
18“ Histoire Naturelle,” first ed., I., pp. 131-133. Kant had read Buffon 
before writing his own cosmogony; see “ Universal Natural History,” Pt. II. 
ch, 2. 
4 Of, “ Systéme du Monde,” first ed., 1796, II., p. 298. 
