On the Sy/tem of Farces, 279 
8, this expreflion,, pels ‘caufes, which modern philofe- 
phy has had fo. much, dificulty to banifh, is inconfiftent with 
the generally adopted ideas, I fhall here offer fome reflec- 
tions on that fubjeét, as well as on Kant’s fyftem of forces 
In my, opinion, the, manner of cultivating natural Meare 
phy ought to be confidered under feveral points of view. 
1ft. Some confine themfelves to a defcription of the objects. 
and phenomena that occur. The zoologift defcribes ani- 
mals, their manner of living, and of reproducing their 
fpecies. The botanift does the fame in regard to plants. 
The mineralogift in the like manner deferibes minerals and 
their external qualities. The phyfical geographer defcribes 
the furface of the earth; and the aftronomer the celettial 
bodies, their movements, &c. 2d. Others go full farther. 
The anatomitt explores. the internal parts big animals and 
vegetables, and defcribes their ftruture ; and the chemift 
analyfes them, as well as minerals, to difcover the principles 
of w hich they are formed. 3d. The geometrician calculates 
the movements and forces of all thefe beings, independently 
of the caufes by which they may be cen 3 and he fur- 
nifhes the mechanift with calculations for conftru€ting and 
dire€ting his machines. 4th. In the lait place, others en- 
deayour to difcover the caufes of all the phenomena exhibited 
by thefe bodies, as well as to explain the mechanifin of their 
different movements. This is the fcience of phyfics. But 
it has fo often Jed men into crror, that true philofophers are 
exceedingly difficult in regard to the explanations it gives. 
This has induced them to have recourfe to the fyflem of 
forces, by which they exprefs a fact, the effects of which 
they calculate without attempting to trace them to their 
caufes: as they cannot, for example, yet explain the pheno- 
mena of vitality, they exprefs them by the words vital force, 
whatever | may be their caufe. The vital force, then, is that 
which produces the phenomena of vitality; but we are ig- 
norant of the manner in which it aéts. This is what bagte 
to be underftood by the expreffion occult caufes. The an- 
T4 : cients, 
