PHILOSOPHY OF NATURE—LEIBNITZ’S IDEAS. 45 
The classification of genera and species in the vegetable 
kingdom is a difficult task. Botanists in the seventeenth 
century thought that distinctions, founded on the shapes 
of the flower, made the nearest approach to the natural 
order in arranging a series of classes. Leibnitz judges 
that it would be best to make the comparison not only in 
respect toa single characteristic, such as that of the flower, 
which may after all be the most useful in arranging a con- 
venient system, but also in respect to the characteristics 
of other parts in plants. He thus suggests the rule of 
subordination in characteristics, as a result of his ideas 
upon the harmony of beings. 
Thus all these labors and hypotheses issue directly from 
Leibnitz’s metaphysical conceptions as to the system of 
_ mundane elements. A still more direct outcome from them 
is the invention of the infinitesimal calculus. Were the 
calculus of itself nothing more than a splendid curiosity, 
even then it would be much to have discovered a means 
of working upon and with infinite quantities as with finite 
ones. Fortunately that method of calculation has found 
occasion in astronomy, mechanics, and physics, for applica- 
tions so rich in results that those sciences have gained a 
new being from it. It is a new instrument, a new lever 
supplied to them for the highest researches. We thus 
learn the extent of Leibnitz’s familiarity with the most 
difficult problems. 
Il. 
What has been the influence of the metaphysics of 
Leibnitz over the great processes of advance in modern 
science, beginning with those of the last century? It is 
an old saying that the eighteenth century had no original 
philosophy; in fact, it lived on borrowed doctrines. It 
had among others one system of teaching proceeding from 
that of Leibnitz, and Diderot may be said to have been its 
