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‘sciences do not, by any means, prove any incompatibility between 
the sciences or their general methods. Apply the truth, and we 
recognize at once that, while there must exist distinctive differences 
between the methods of any science, or of all the sciences, and the 
methods of philosophy, these distinctive differences are no proof of 
incompatibility between philosophy and sciences or between their 
methods. 
More than that, the method observed by all sciences is, in its 
ultimate analysis, generalization, which is a process of abstraction. 
Without generalization, without abstraction, it would be simply 
impossible to rise from the notion of fact to the notion of law. 
When the chemist finds that this oxygen, in this balloon, takes just 
so much of this hydrogen in this balloon in order to combine into 
water, he extends this proportion to all oxygen and all hydrogen, 
and to all experiments with them—past, present and to come—not by 
scientific observation, but by generalization, by abstraction, by the 
fundamental process of all thinking. When the physicist finds that 
this piece of spar gives double refraction, he concludes the same of 
all samples of that substance, and that without at all needing to 
experiment with the rest. When the physiologist finds that the 
blood in this man is composed of white and red corpuscles, he 
does not need to dissect all mankind in order to reach the conclu- 
sion that the blood of every man is composed in the same way. 
Thus we recognize that science is constantly making use of one 
great operation, which is the fundamental unity of all scientific 
method, and that is generalization, abstraction. 
Then comes the mathematician, whose method means abstraction 
on ahigher plane. He shows that two and two make four, whether 
it be two and two atoms, or two and two planets, or two and two 
ideas; and he applies his principles of number and weight and 
measure, his notions of quality and equality and proportion, to all 
things, and works out at his desk the system of the universe. It is 
a remarkable fact that the great fundamental, dominant principle 
of all physical science in our age, the conservation of force, was 
wrought out mathematically, by Leibnitz, one hundred and fifty 
years before it was proved experimentally by Joule. 
One step more up that ladder of abstraction and we reach the 
operations of philosophy. It widens our view, giving us not merely 
the perspective of this science and of that science and of all sci- 
ences lying side by side, interlacing and working together in the 
